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TRANSCRIPT
SEDIMENT SOURCES AND FLUVIALGEOMORPHIC PROCESSES
OFLOWER NOVATO CREEK WATERSHED
Report toMarin County Flood Control and Water Conservation District
by
Laurel Collins2338 Valley St
Berkeley, CA 94702.. (510) 549-1209
J~,)«.4- S(() '. 5'1- I..f ,-- ~ to if
.t1/~ 51 L~ J -:;-:1. -, '(j 4--1.6
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JULY 1998
SEDIMENT SOURCES AND FLUVIALGEOMORPHIC PROCESSES
OFLOWER NOVATO CREEK WATERSHED
Report toMarin County Flood Control and Water Conservation District
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by
Laurel Collins2338 Valley 5t
Berkeley, CA 94702(510) 549-1209
JULY 1998
TABLE OF CONTENTSACKN'OM..EI:X.'i~ ivEX.ECUTIVE SUMMAR.Y vwmODUcnON 1OBJECTIVES _ ~....................•.............. 1BACKGROUND AND HISTORY OF NOVATO WATERSHED 4Flood. Control Management Activities 8USGS Gage Records 10G~~OOO1.,()(i1ffi 11Field Reconnaissance 11Locally Intensive Field Measurements 12·Interpreta.tion of Aerial Photographs _ 14RESl.JL1"S AND DISCUSSION ,;. 15Novato Creek 15Findings for the Tidal Reach Downstream of Diablo Avenue Bridge. ISBani< Condition ~ ! •••••••••••• 15Sediment Cores 15Findings for Novato Creek Upstream of Diablo Avenue Bridge 22Ban.k Conditions ; 22Bed Condition Relative to Pools and Wood ..•....._ 30Ban.kf'ull Geome'tr)' 35Rosgen Classification 38Comparison to Earlier PhotoglCl:phy and Channel Bed Incision 42Reading Trees and Rates of Incision 46Comparison to Previous Studies 47Changes in Drai.nage Densit:}' 48Roads and Urban Runoff 49Hillslopes and Landslides along Mainstem Novato Creek 49Conclusions for Mainstem Novato Creek 50BO'WMAN' CREEK. •••••••••••••••••••••••••••••••• ••••••• 52LEVERONI CREEK ~ 63VINEY"A.RD CREEK 64General Background 64Channel Geometr}' 64Bed Condition Relative to Pools, Wood and Sediment Storage 6SChannel Incision 65Hillslopes and Landslides in Vineyard Watershed 68Roads and Urban Influences 68Conclusions for Vineyard Creek 68
WARNER CREEK 6.9.................•................•.....SUMMARY CO.NCLUSIONS 73RECO~ATIONS 75
REFEREN.CPS 76................................................................
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APPEN....QIX A Watershed MapsAPPENDIX Al Novato Creek Field Notes Above Diablo Ave.APPENDIX A2 Novato Creek Data Tables for Above Diablo Ave.APfENDIX A3 Novato Creek Reference InformationAPfENDIX A4 Novato Creek Reference FiguresAPfENDIX AS Novato Creek Tree A2e Analysis.....A.....PP.....E=N.....ID.....I.....X......B=- .&.N...,.o.....v.=.at_o:....:C.....r-=e.=ek~Fi~el'LNOleS Channelized _Reach Below
Diablo Ave B.ridge and Novato Creek Data Iables forBelow Diablo Ave.
APPENDIX CAPPENDIX 12APPENDIX EAPPEN..DJX FAPPENDIX GAppendix H
Field Notes Arroyo AVichiField. Notes Bowman CreekField Notes Leveroni CreekField Notes Vineyard CreekField Notes Warner CreekNovato Creek Bank Condition Chart.
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ACKNOWLEDGMENTSI thank Liz Lewis for her commitment to the collection of field data, DaleHopkins, joanna Charlton, and john Neville for their field assistance and joshCollins for his technical review.
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EXECUTNE SUMMARYThis is a report of a field and office study of sediment sources andgeomorphic changes within the lower Novato Creek drainage network. Thefield work was restricted to the main stem channel and selected tributariesdownstream of Stafford Dam. The Marin County Flood Control and WaterConservation District (the District) requested this study to explore ways toreduce dredging needs but preserve flow capacity in the Phase 1-4 segmentsof the Novato Flood Control Project (NFCP or the Project). The report includesanalysis of historical conditions uncovered through library searches and fieldwork, and analysis of existing conditions based upon detailed maps of channelterraces, bed and banks, coring of past sedimentary deposits, dating ofchannel changes by rephotography and tree ring analysis. The results arereferenced to study reaches that are delineated by bridges and confluencesfor easy recognition on existing maps 'and photographs, and for futureinvestigations.
This report is consistent with the fundamental concepts of river and streamscience. It is assumed that the usual or average physical form of the streamdepends upon the average supplies of water and sediment that enter thestream from its watershed. Extreme events such as drought and deluge cancause significant changes in the location and configuration of a channel, butover time the average form of the channel will be re-established. There aremany complicating details, but in essence the channel bed will erode if thereis a general decrease in sediment supply or an increase in water supply.Vertical erosion of the channel bed results in lateral erosion of the banks ofthe channel, and perhaps erosion of the terraces, which are above the activebanks. Vertical erosion is also called channel degradation, downcutting, orincision. Vertical erosion cannot happen unless the sediment can betransported downstream. A channel becomes entrenched when it holds floodflows that are twice the height of bankfull flow. The transport capacity of thechannel is a function of its slope and discharge. Channel slope, width, depth,sediment transport capacity, and the volume of water flOWing through thechannel are interrelated. Change one of these parameters and the others willchange in predictable ways. The predictable nature of these relationshipsprOVides a basis for watershed analysis.
This study was not designed to prOVide any engineering specifics. The studyhas produced a general analysis of watershed conditions that can lead to morespecific, quantitative analysis of land use changes or new engineering to solvelocal problems with water and sediment supplies.
During the last 165 years, or since the local advent of modern land uses, theNovato Creek watershed has experienced a major shift in dominant sediment
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supply from landsliding on the hillsides to bank and terrace erosion of thechannel network. This shift in the source of sediment has caused increases inboth sediment and water supply. The increase in water supply is due to localincreases in surface water runoff, rather than groundwater or water importsfrom another watershed. The increase in runoff has been caused by acombination of intensive grazing and urbanization, both of which havesignificantly decreased infiltration and the water holding capacity of thewatershed. The increase in sediment supply is due to the channel adjustingto the increased runoff.
The result is ongoing entrenchment or down-cutting of the channel networkand bank erosion throughout the upper reaches of the channel network andinto much of the lowland valleys. This erosion will continue until thechannels are wide enough to enable the formation of a stable, vegetatedfloodplain between the terrace banks. The patterns of upstream down-cuttingand downstream in-filling are predictable responses by the channel system toalterations in water supplies.
Two episodes of accelerated erosion can be discerned from the distributionand ages of overstory trees along Novato Creek. The first period appears tohave started dUring the 1830's, when the watershed began to supportintensive grazing and agriculture. The second episode, which continues today,appears to have begun during the 1950's, and probably relates to the functionof Stafford Dam as a sediment trap for the upper 8.4 sq mi. of the watershed,and to the urbanization of the lowland valleys. These two time periodsaccelerated erosion rates during t;he last 200 years.
The primary source of sediment for Novato Creek is local bank and terraceerosion. Part of the sediment supply moves in and out of temporary storageon point bars, lateral bars, and behind debris jams within the channel bed.The upper reaches of the channel network have the capacity to transport thesediment supply downstream to the flood control project. Much of thesediment that reaches the project tends to be stored there. The flood controlchannel causes the water surface slope to flatten, and hence there is a loss ofsediment transport capacity. The NFCP is essentially a trap for sedimentderived from upstream bank and terrace erosion. The supply of sedimentreaching the NFCP from landsliding, dry ravelling, surface erosion, and thetides is probably orders of magnitude less than the supply of sediment fromthe channel banks, bed, and terraces.
Sedimentation within the tidal reach of Novato Creek is encouraged by therailroad crossing and tidal marsh reclamation. The railroad crossing is abottleneck. The cross-sectional area of the channel at the railroad crossing is
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much less than required for downstream transport of sediment reaching theflood control project. Historical reclamation of the tidal marshlands hascaused a significant loss of tidal flows to and from the tidal reaches of thecreek. The channel has narrowed and aggraded in response to the decrease intidal flows. The entire length of Novato Creek downstream of the railroadcrossing is less than one half its historical width and depth.
Rapid sedimentation within the flood control channel will continue given thepresent scenario of increased runoff throughout the valleys and headwardreaches of the watershed, chronic channel entrenchment above the tidalreach, an undersized railroad crossing, large-scale tidal marsh reclamation,and an excessively wide flood control channel. Modem land uses haveincreased the sediment supply from the upper parts of the watershed, anddecreased downstream sediment transport capacity, especially within thereaches of the tides. This has increased the flooding hazards on the reclaimedand urbanized tidal marshlands, and decreased the efficacy of the floodcontrol project. Simply stated, an upstream problem of channel degradationhas become a downstream problem of channel aggradation.
Overall rehabilitation of the watershed would begin with reduction of runofffrom urbanization and grazing, raising the railroad crossing, and large-scalerestoration of tidal marshlands. This would begin the restoration of ecologicalresources along the creek while decreasing flood hazards. It is not clear fromthis study what amount of urban setbacks would be required to -enable thechannel to achieve a stable configuration between its terrace banks. It isclear that without such an approach there will be an ongoing need torepeatedly build and repair erosion control structures for most of the banksand channel bed of Novato Creek. In the absence of watershed restoration,the flood control project will not be able to cany its design capacity dischargewithout frequent and regular dredging.
If an objective of the District is to reduce the frequency of dredging in thetidal reaches of Novato -Creek, then the NFCP above the tidal zone should beredesigned and managed as a sediment catchment basin.
Principle objectives and related study results
Determine the location of sediment sources.The locations of major sediment sources are pervasive terrace' andchannel bank erosion throughout the channel network from largest tosmallest stream order.
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Determine the processes by which sediment is being producedand supplied to the stream system.
The major process by which sediment is being produced and supplied tothe stream system is from fluvial erosion of the channel bed and banksfrom flows that are equal to or above bankfull and that have increasedin frequency during the last century and a half.
Determine change through time and space of sedimen t sourcesand landscape processes.
Change through time and space of sediment sources and landscapeprocesses is indicated by a shift of the most active sites of erosion fromhillsides to the channel network, and from the valley bottom channels tothe headwater channels. The large high-order channels along the valleybottoms may have passed through their peak rates of inCision and arenow aggrading in some restricted areas. Bank erosion, on the other hand,will likely continue until the channels are wide enough to form a newfloodplain within the entrenched channels. The large high-orderchannels, if left entirely to natural processes, will likely become stablesooner than the headward, small order reaches, which began to degradelater.
Determine, if possible, the extent to which the drainage densityhas changed.
There have been large and sudden historical changes in drainagedensity. The early construction of irrigation and drainage ditchesincreased drainage density in the valleys, whereas the reclamation oftidal marshland decreased drainage density within the tidal reaches of
. the watershed. Since the advent of irrigation, there has been a furtherincrease in drainage density above the tidal reaches due to gullying inthe headward rangelands and the addition of storm drain,S in theurbanized lowland valleys. Drainage density has also been increased bythe incision of alluvial fans that once separated the tributary channelsfrom the main stem channels.
Identify reaches for intensive monitoring of future changes inchannel profile and geometry.
Study reaches have been established through this study. These studyreaches should be considered for an ongoing program of locallyintensive empirical observations of the sources and disposition· ofsediment and water supplies within the watershed. There should bedeveloped a system of repeated observations among these studyreaches that would enable a fluvial geomorphologist to recognize
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changes in the relative importance of natural processes and land use onsediment and water supplies. Some of the details of the requiredmeasurements may be provided by this report.
The purpose of an ongoing monitoring program should be to understandinterrelations among upstream and downstream events and processes.For example, there needs to be an operational understanding of thefeed-back mechanisms between upstream land use or climate change,downstream grade change, flooding, dredging and upstream riparianhabitat loss.
Discuss observations about the relative abundance of tidalversus terrigenous sediments within the NFCP from Diablo Aveto the NWPRR Bridge.
The abundance of fine silt and clay-sized sediment versus sand andlarger-sized sediment increases towards the marsh. The sand andlarger-sized sediment is certainly derived from terrigenous sources, butit is unclear how much of the fine-sized sediment is derived from thetides. Additionally, fmes from the uplands can be reworked byincoming tides. Sand and larger-sized terrigenous sediments comprisedmore than 50% of the sediment volume for the upper 2/3 of the NFCP in1997. The amount of clay-sized sediment from the uplands mayrepresent anywhere from another 10-40%. Following the 1998 winter,it is likely that the percentage of sand and large-sized terrigenoussediment was substantially greater than 50% of the total sediment fromDiablo Ave. to the NWPRR Bridge.
Provide recommendations for reducing upstream sedimentproduction.
General Recommendations
This study indicates that the greatest changes in Novato Creek haveevolved from increased runoff. Therefore, the long-term solution wouldbe to reduce runoff from both urban and grazed landscapes. To reducerunoff from grazed lands, regulations restricting heavy grazing practicesand encouraging best management practices would be needed. Toreduce urban runoff, there is a need for urban development plans andordinances that promote inflltration and discourage the concentration ofrunoff into storm drains that serve as point sources of excess flow to thenatural channel network. A new storm drain system could be designedto ultinlately bypass Novato Creek.
Specific recommendations
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1. Stabilize many of the precariously undercut trees on the high terracebanks before they collapse into the channel and cause bank erosion toproceed unchecked from loss of root strength in the banks. This wouldalso help preserve an important ecological and aesthetic resource.
2. Consider restoration techniques to divert high velocity flows andassociated high shear stresses away from eroding banks.
3. Consider converting more of the diked marshlands into functionaltidal wetlands that would dissipate flood flows and increase channelcapacity for sediment transport by increasing tidal prism.
4. Consider piping urban runoff· into a separate and constructed drainsystem that does not connect to Novato Creek but leads separately to aflood control basin in the wetlands or to San Pablo Bay. This wouldeffeCtively reduce the amount of water going into the channel, whichcould. reduce flood fr~quency and associated damages. Consider thatwater caught in a basin before going to San Pablo Bay could be filteredby natural vegetation.
5. Consider constructing on tributary channels such as Arroyo Avichisediment traps that would funnel some, but not all of the bedload awayfrom Novato Creek into a separate catchment.
6. Reduce the input of fine sediments from cattle trail crossings byfencing the main tributary channels of Bowman and Leveroni Creeksfrom cattle access.
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BACKGROUND AND HISTORY OF NOVATO WATERSHEDThe sediments that are deposited in the NFCP have two primary sources, SanPablo Bay and the Novato Creek watershed, including its tributary streams~
The Bay source is termed tidal, and the watershed sources are collectivelytermed terrigenous.
Tidal sediments are fme-grain silts and clays that are carried into the floodcontrol channel as the suspended sediment load of the rising, or flood, tide.These tidal sediments have terrigenous sources, but they are re-worked andmixed within San Pablo Bay and the tidal reaches of local streams before theyare deposited in the NFCP. In general, the tidal sediments are moved bystream flow and falling, or ebb, tides from local streams to deeper bay waters.Tidal currents deliver a portion of these sediments into shallow waters andonto mud flats, where they are temporarily stored before they areresuspended by wind-generated waves and carried landward by the risingtides. The deposition and resuspension of sediments from deeper to shallowerwaters separates the fmes from the coarser sediments, such that only thevery fme sediments reach the landward margins of the Bay. Dredging in SanPablo Bay may temporarily contribute to the suspended sediment load of thetides. Since the NFCP exists at the landward margin of the Bay, it can be aplace of deposition for fme-grain tidal sediment.
Terrigenous sediments are derived by numerous kinds of erosion fromhillsides, stream terraces (abandoned flood plains), stream banks, and channelbeds. Hillside processes that can generate sediment include dry ravel fromsteep slopes, rills and gullies, and various kinds of landslides. These processesare not very important to the NFCP unless they provide sediment into thestream system. Terrace and bank sources include lateral erosion (also calledretreat) and tree fall. The channel bed can be a sediment source if the beddegrades, meaning that it cuts down or incises. Channel degradation can leadto bank and terrace undercutting, which can lead to bank retreat and tree fall.The sediment that enters a stream or is derived from it can be storeddowstream through bed aggradation (in-filling). Sediment bars, debris jams,and man-made dams are sediment storage features. A bar or debris jam maypersist for many years, although the sediments that comprise the bar or thatare stored on the bed surface behind a debris jam change, as sediments aredelivered from upstream sources, and then pass through the bar or jam ontheir way downstream. Landslides, bank failures, and the loss of debris jamscan generate large pulses of sediment.
All of these terrigenous sources of sediment interact with each other in rathercomplex ways. And their interactions are affected by climate,geology, and
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land use. A review of the overall environmental character of a watershed andits land use history is required to understand the relative importance of tidaland terrigenous sediment sources.
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Novato Creek drains eastward to San Pablo Bay, Figure 2. Watershedelevation ranges from less than 0' to ~bout 1900' National Vertical GeodeticDatum (NGVD) and mean annual precipitation is about 28". The estimatedmaximum high tide above Mean Sea Level (MSL) is 6.5' (also equal to 9.5'above the datum for the San Francisco Tide Station) (1983, Camp Dresser &McKee Inc). The total drainage area of Novato Creek at its mouth is 44 sq mi.There are six major tributaries: Arroyo Avichi and Warner Creek which haveconfluences downstream of the Diablo Avenue bridges and are confluent toNovato Creek within the tidal reach; Vineyard and wnso~ Creeks, which aretributaries to Warner Creek; and Bowman and Leveroni Creeks which enterabout a mile and a fifth of a mile downstream of Stafford Dam, respectively.The dam is about 4 miles upstream of the NFCP. It captures water from theupper 8.4 square miles of the watershed and was completed in 1951.Drainage area for each of the tributaries is reported below in Table 1.
M·lesSAe . ralnage rea In .Quare . I
Novato at mouth 44Novato at Redwood Blvd 24.5Novato Creek above the NFCP 18Arrovo Avtcht at mouth 1.8Warner Creek at mouth 5.1VineYard Creek at mouth 2.6Wilson Creek at mouth 1.9
Creek at motith 3.1ILeveroni Creek at mouth 2.1
TabI 1 D .
This study focuses on the drainages below the dam, since bedload is capturedby the dam and only suspended sediments are transported from the upperwatershed during uncontrolled winter flows over the spillway. In 1985 thespillway was raised and its width was decreased to increase flood storage .
Major landscape features in Novato watershed include steep hillsides,underlain by Franciscan bedrock, and a broad flat valley composed ofQuaternary-aged alluvium. The older alluvium is a terrace, which is anabandoned floodplain. Bay muds are found across the plain of the formertidal wetlands that extended to San Pablo Bay. In·the watershed upstream ofStafford Reservoir and on the south-facing slopes of Burdell Mountain ridgebelow the dam, where grasslands predominate, dairy ranching is the principalland use. Suburban development is advancing onto north-facing slopes whereoak-bay woodlands predominate. Some of the woodlands may have been·
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altered by early settlers during the mid 1800's when chopping and exportingof wood was also a principal industry in Novato (verbal communication fromstaff at the Novato Historical Society).
The alluvial valley below Stafford Dam has been almost entirely altered byresidential and commercial development. There remains a ribbon of riparianforest along Novato Creek which supports bay, willow, ash, and buckeye trees.Elderberry and walnut are infrequent. Alder trees, abundant in watershedsto the west and south, are very rare to absent along Novato Creek. Coast liveoaks and valley oaks are commonly found along the valley flat and at theedge of the terrace banks, which stand about 10' - 14' above the channel bed.
The valley bottom may have had open-range cattle grazing as early as the1820's, after the mission in San Rafael was established. Before this period thevalley flat probably supported a mixture of oak and grasslands. Mexican landgrants were given for Rancho Novato In 1839. By 1856, thousands of appletrees had been planted in the valley and Novato became one of the largestapple orchards in the world (Novato Chamber of Commerce). A photocopy ofa circa 1860 (1) etching of Rancho Novato is provided in Appendix A4.Theoriginal is at the Novato Historical Society Museum. As early as this time,flow from tributaries, such as Warner Creek, had been altered and ditched forirrigation. The etching shows a riparian corridor along Novato Creek but notalong Warner Creek, suggesting it had been recently constructed as a drainageditch. A 1909 Subdivision Map, APpendix M. also shows it as a ditch.
The extensive tidal marshlands and the network of sloughs at the easternmargin of the alluvial valley were diked and drained for agriculture aroundthe 1860's. At this same time, there was also rapid sedimentation andbayward growth of the marshlands due to deposition of hydraulic miningsediment from the Sierra Nevada. Levees were built along Novato Creek toreclaim the new marshlands that developed during this wave ofsedimentation. Novato Creek was thus extended toward the bay. The leveescut off the distributary sloughs from tidal flow and prevented upland floodsfrom dissipating over the marsh surface. This loss of tidal prism caused thetidal reaches of Novato Creek to narrow and shallow, thus altering the abilityof the channel to transport terrigenous sediment. Transport of uplandsediment out of the watershed became less efficient.
Dedrick's research (1992) has shown narrowing of Novato Creek Slough since1854. By 1941 a 1500' segment near the mouth was only about 10% of itsformer width, see Table 2 below. During the previous century, Novato Creeksupported commercial navigation (Dedrick 1993), suggesting that the channelwas also deeper, not just wider. Figure 3 shows a circa 1895 photo of a sloop,
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the Solferina, approaching the landing near the present Novato Fair ShoppingCenter on Redwood Blvd. Further references to this photo are in AppendixA4. Today, the Novato Fair bridge is the headward maximum extent of tidalaction, and has insufficient tidal flow to function for navigation. The channel·must have been several feet deeper in the historical past.
C k T"d I R h W·d h ChT bI 2 Na e . ovato ree 1 a eac 1 t aneesYear !Width of Novato Sloueh at distance from San Pablo Bav
100' 500' 1000' 1500'1854 1170' 1110' 840' 740'1898 380' 290' 260' 290'1921 290' 170' 160' 190'1941 90' 70' 80' 80'
From Dedrick (1992).
Novato Creek tidal reach, between Warner Creek and the NWPRR Bridge, wasstraightened and channelized sometime after 1912, but before 1935 (comparethe 1912 USGS topographic map, Appendix A4 to 1935 photograph, Figure4A). This is roughly estimat~d to have occurred around the mid 1920's. Anestimated 1,720' of channel length was removed by channelization. The USGSmap does not properly delineate the location of Novato Creek below Diablobridge; a drainage ditch is mistaken for the main channel. This study.recreates the original Novato Creek alignment from the 1935 photo, Figure 4B.
Flood Control Management ActivitiesConstruction of the NWPRR also had significant impacts upon the tidal andterrestrial flood flows from Novato Creek. The low steel, on the railroadbridge and the top rail intersect flows that occur at 6.58' and 9.35' above msl,respectively (Camp Dresser & McKee, Inc, 1983). Extreme high tides alonecan overtop the rails. High flows that coincide with high tides, for example inFebruary 1998, intersect the NWPRR Bridge and cause local flooding.Additionally, woody debris becomes trapped at the upstream edge of thebridge, exacerbating flood damages, Photo 9. The obstruction to flow hascaused backwaters to extend into downtown Novato and have augmenteddeposition of sediment within the NFCP. The February 1998 floods causeddamages to sections of the NWPRR Bridge and the bed beneath it to aggrade.Its replacement will be required (verbal communication, Liz Lewis, CreekNaturalist MCFCWCD).
The existing Phases 1-4 NFCP were started in 1987 and completed in 1991. Itinvolved some excavation, realignment, widening, construction of trapezoidalchannel banks, and levees. Presently, flows less than 3,300 cubic feet persecond (cfs) (determined at the USGS gage upstream of 7th St Bridge), areconfmed within the NFCP, unless: 1) the design capacity is reduced by
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sedimentation; and/or 2) the flooding doesn't coincide with high tide.Dredging of this reach every three to four years is required in this reach tomaintain the design capacity, 50-year flood protection (verbal communicationfrom Liz Lewis). In 1996 the MCFCWCD dredged 45,000 cubic yards ofsediment from a I-mile segment of Novato Creek and a 0.3-mile segment ofWarner Creek tributary. Dredging has been done every few years since theconstruction of the Flood Control Project.
The MCFCWCD management activities from Diablo Avenue to Novato Blvd.Bridge at station 131-40' (Watershed map #4) include maintenance activitiessuch as removal of woody debris that obstructs flow, trimming and/orremoval of willows or cattails (Typha sp.) that have encroached upon thechannel bed, and construction of bank stabilization structures. Upstream ofNovato Blvd. bridge, portions of Novato Creek are within private property andopen-space lands. Within these lands, the stream course is not activelymanaged. A small segment just downstream of the dam is maintained by thelocal water district.
USGS Gage RecordsThe USGS gage is within the proposed Phase VIII Flood Control Project thatextends approximately 4,500' from Diablo Ave to Grant Avenue Bridge. Atthe gage, discharges of 3,300 cfs have approximately a 26-year recurrenceinterval (see Appendix A3, Flood Frequency Curve from Jim Fain, MCFCWCD).Thus flooding in the reach between Diablo and Grant Bridges is predicted tobe more frequent than flooding downstream in the NFCP. Additionally,because culvert outfalls (inverts) of small tributaries and urban storm drainsare below the 3300 cfs, local flooding from these drains occurs beforeoverbank flooding on Novato Creek.
During the 52-year period of record, the most significant flooding occurred in1982 with an estimated 5,000 cfs at the USGS gage station. The secondhighest flow, 3,194 cfs, occurred February 1998 (see Frequency Analysis Datain Appendix B3). According to the Flood Frequency Curve, the "bankfullflow", as defined by a recurrence interval of about 1.S years, would produce adischarge of about 500 cfs. Bankfull flow corresponds in elevation to thelevel of the floodplain, when one is present. From Diablo Avenue Bridge toStafford Dam, Novato Creek typically has a poorly developed to nonexistentfloodplain. This is because the channel is entrenched, which means that theratio of floodprone width (measured at twice the height of maximum bankfulldepth) to bankfull width is less than 1.4. This is called the entrenchmentratio, after Rosgen (1996). Entrenched channels are inherently unstable.Changes in water and sediment supply, as affected by land use, are causingthe channels to rapidly adjust their width, depth and slope. The rate of
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adjustment is rapid enough to indicate instability, or disequillibrium. Astable channel has hydraulic geometry that is maintained over time; eventhough the channel may be laterally migrating, it neither aggrades ordegrades and its gradient remains constant. I
GaffiRALMElHOOOLOGIffiA complete survey of the sediment sources throughout the watershed wouldhave been beyond the intended scope of this study. The required generalcharacterization of the sediment sources was achieved through a combinationof field reconnaissance, interpretation of aerial photographs, and locallyintensive field measurements in selected areas of typical terrain from theupper limits of some tributaries to the tidal reach of the mainstem channel.
Field ReconnaissanceDuring late spring through fall 1997, the mainstems of Novato Creek and itstributaries Arroyo Avichi, Warner, Vineyard, Bowman and Leveroni Creekswere walked by the author and tiz Lewis. A tape was stretched so that noteson channel characteristics could be correlated to a general field location.Other than a 7.5" USGS quadrangle, a base map of the channel was notaVailable at the time of the reconnaissance and it was not of sufficient scale tomake ·distance station notations, so all field notes were originally referencedto their taped distances and not mapped on location. The Novato Creek FieldNotes above Diablo Avenue Bridge arein~. Specific field methods·and standards are deScribed at the beginning of the Field Notes. For all data
. and graphs, references to right and left bank are for looking toward thedownstream. Distance Station 0 + 0.0 is located at the upstream edge ofDiablo Avenue Bridge. Distances are reported as negative values upstream ofDiablo Avenue Bridge and positive values downstream of the bridge. Theyare written in standard survey notation. The extent of each channel reachstudied is reported below.
. sancepo Id RI S d' d d ith f Che . enst 0 anne tu Ie ur n2 Ie econnalsNovato Creek uDstream of Diablo Avenue Bridee 26265' 5.0 miNovato Creek downstream of Diablo to NWPRR 6,500' 1.2 miBrideeArrovo Avichi mouth to uDstream 10467' 2.0miBowman Creek mouth to UDstr'eam 2974' 1.8 miLeveroni Creek mouth to uDstream 1070' 0.2 miVineyard Creek mouth to uDstream 10110' 1.9 miWarner Creek mouth to uDstream 6600' 1.2 mt
Tabl 3 L
Channel bed condition was assessed with regard to woody debris and pools.,,Notes were also made of the number and type of trees that had fallen across
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the channel or that had become uprooted. Trees that intersected bankfull flowwere noted separately from trees that had fallen across the terrace banks.Trees that were still rooted but slowly slumping or leaning into the channelwere not counted, for example see Photo 43 as opposed to 238. Woody debrisjams were described by their location and condition, such as whether theywere blocking the entire channel, partly blown out, or remnant from a formerdebris jam. Pool locations were measured only if their low flow depthexceeded or equaled 1'. The pools were measured during fairly steady flowthroughout the summer, as maintained by specified flow releases from thedam (liz Lewis personal communication). Pools were also categorized bytheir cause. For example, if the pools were formed by natural channelcurvature (i.e., bends, bedrock or lateral bars), their cause was identified asnatural. Large, natural woody debris (LWD) was regarded as a special typeof natural cause of pools, due to its ecological importance. Pools that werecaused by man-made objects such as cement abutments or rip rap that hadslipped from the banks or had been transported downstream were classifiedas having unnatural causes. These classifications permitted an analysis of thedifferences in pool forming mechanisms among the different reaches. Theraw data are located in the Novato PoolslWood Data Table, Appendix A2.
Photographs were taken of different features along Novato Creek. Thesephotos are arranged in Photo Albums I and II. The Albums are arrangedwith the downstream photos fIrst, and the upstream photos last for each ofthe six channels. Photos and field notes are cross-referenced to distancestations on the Watershed Maps (Appendix A) and to each other.Photographs from previous years were obtained to rephotograph the sitesand determine potential changes. In particular, many photographs from 1987were used from the report on Novato Creek Erosion Control Study (1987,Stuber-Stroeh. Inc) to analyze potential change over a 10-year period. TheNovato Creek photos and rephotography, in Photo Album I, are interspersedwith the 1997 reconnaissance photos so that the downstream to upstreamorder is consistent. Some additional older photos from unidentifiedindividuals are also included. The station distances assigned to the olderphotos are very approximate, since their location in the field was notestablished during the rephotography.
Reconnaissance of the headwater channels in Bowman and Vineyard Creekswas conducted to determine if the small 1st order channels were stable,incising, or aggrading their beds, and!or widening their banks. Field notesand photos for the small tributaries were keyed to locations on USGStopographic maps, located in corresponding figures for each relevant channel.
Locally Intensive Field Measurements
12
Height measurements were made from the thalweg (deepest point in thechannelbed at any given location) to a key feature identified in the field, thatcould also be observed on the older photograph, (Photos 55 and 56 forexample). The measurement points are identified with arrows on thephotographs. The photos also have "x's" that serve for match points. Theoriginal numbering system was left on the older photos so they could becross-referenced to their original Stuber-Stroeh Location Maps in AppendixM. The field notes and photos for the following creeks can be found in thefollowing Appendices:
Photo Album I Novato Creek DST of Appendix JjDiablo Avenue Brid~e
Photo Album 1 Novato Creek UST of AppenQix AlDiablo Avenue Bridge
Photo Album II Arroyo Avichi A dixCPhoto Album II Bowman Creek Annendix DPhoto Album II Leveroni Creek Annendix EPhoto Album II Vineyard Creek \nnendix FPhoto Album II Warner Creek ~. h
For selected reaches of the mainstem channel, bank condition was assessed asthe amount of erosion and the abundance and types of revetment along theright and left banks. The banks were divided vertically between bankfull,.usually less than 5', and terrace, ranging from 5'-14' in height, and then notedrelative to station distance. Many banks were bare due to a complex offactors, including dense shading of the riparian floor and the alleopathic soilconditions beneath the bay trees. However, the banks were not considerederoding unless they had a threshold of 0.5' average bank retreat. Exposedtree roots proved to be excellent indicators of the amount of bank loss, seePhotos 38 and 50 for example. In a few areas, the volume of sediment storedin bars was measured by measuring their width, length, and height above themean bed level. Types of bank revetment and erosion control structureswere identified and their lengths were measured along the centerline tape.Their vertical extent on the bank was not quantified. The raw data arelocated in the Novato Banks Data Table, A,gpendix A2.
Repeated measurements of bank condition in 1996 and 1997 along thechannel centerline did not match precisely, particularly in the reach upstreamof Sutro Avenue Bridge. Later notes on bank condition were referenced tothe earlier notes on channel distance. Although the measures of relativeamounts of different bank conditions for different years are comparable, the
13
•
I
[
' ....
measures are not geo-rectified and therefore, their exact location in the fieldmay be slightly off, as well as their actual length.
The distances measured in the field were later put on Watershed Maps 1-6which can be found in Appendix A. These maps were supplied by the MarinCounty Community Development Agency after most of the measures of bankand bed condition had been completed. Planform position of creeks on thesemaps is not exact, especially because much of Novato Creek is hidden beneathits riparian canopy. These maps were the best available base maps forplotting station distances recorded in the Field Notes. .Based upon fieldsketches of channel bends, adjustments were made in the alignment of thechannel on these maps. For example, the new adjustments are shown in blackink and the fonner outline of the creek is shown in solid blue, see WatershedMap 4 for example. These maps do not reflect channel width, and theirdegree of accuracy, relative to their pre-existing planfonn or addedadjustments, is not known.
Elevations relative to terrace height and bed height were made on certainselected trees that were growing within the terrace banks. Measurement ofdiameter (DBH) were made for selected trees and their coring was planned topermit development of correlations between tree diameter and tree age..Based upon such correlation, local rates of channel incision might be derived.Unfortunately, the quality of some of the tree specimens prohibited coring.
Bank condition and revetment type was also measured downstream of DiabloAvenue Bridge along the tidal reaches of the NFCP. These measurementswere taken in January 1998 when the channel was not wadeable, so a tapewas pulled along the top of the left bank to the Redwood Blvd. Bridge. Belowthis point, most of the channel banks are earthen with levees, but channelshape is still a wide trapeZOid. One type of revetment found between Diabloand Redwood Bridges, but not found upstream of Diablo was "Annorlock",which was used to maintain the constructed trapezoidal banks.
In May and again in October 1997, the channel bed within the tidal reach ofthe NFCP was cored to determine size characteristics and spatial distributionof sediment deposited in the bed during the 1997 Water Year. The NFCP wasdredged the previous fall of 1996. The coring was performed by the author,with assistance from Liz Lewis and other MCFCWCD staff. Field methods andstandards are described in detail at the beginning of the Field Notes for theChannelized Reaches, Appendix B. The raw data are located in Appendix B1.
Interpretation of Aerial Photographs
14
Field recortnaissance of the hillsides in Bowman Canyon was conducted by theauthor and liz Lewis to verify landslide mapping interpreted from stereoaerial, black and white photographs taken in 1995 (scale 1:12,000) and 1950(scale 1:6,000). The 1950 photos only covered the northern portion of thecanyon. The purpose of the landslide mapping was to identify whether slideswere contributing sediment directly to the channel network. Delineation oflandslide types was not considered necessary for this analysis. Instead, onlylandslides that appeared to be recently active within the last 25 years weremapped. Landslide mapping was not performed for the rest of the lowerwatershed because the woodland canopy hid many of the landscape featuresand because it was beyond the scope of this study.
RESULTS Al.ID DISCUSSIONNovato CreekBndings for the Tid&.Reach DOwnstream ofDiablo Avenue BridgeBank ConditionThe lateral extent of eroding banks and revetment within the NFCP wasmeasured to compare bank condition to upland reaches and to show whetherany of the sediment within the NFCP was locally derived. The raw data arelocated in the Channelized Bank Condition Table, Appendix Bl. Figure 5shows two pie charts that represent channel conditions from Diablo Avenue toRedwood Blvd. bridge crossings. The top diagram shows the percent length ofstable and eroding trapezoidal banks and the percent revetted bank, while·the lower diagram shows the total percentage of different types of revetment
: used. Stable banks represent 37% of the length, while only 4% of the channelbank is eroding and contributing sediment to the project bed. About 58% hasbeen revetted. Most of the revetment is poured concrete walls. Natural bankconditions do not exist along this reach.
Sediment CoresWatershed Map 1 shows the locations of the different coring stations. TheField Notes are locatedin~. Figure 6 shows a plot of the bed coresthat were taken in May 1997 in the tidal reaches of the Flood Control Project.The single cores were located about 33' to 40' from the left bank. The figureshows cores from upstream near Warner Creek confluence, on the left side ofthe page, to downstream of the NWPRR Bridge on the right side of the page.The data show that sand-sized sediment extended to at least 3,755'downstream of the zero station at Diablo Avenue Bridge. Gravels were foundfurther downstream than core station 3 (23+85') which is near the confluenceof Arroyo Avichi. Station 2 had gravel up to 10 mm in size within the corenear Warner Creek confluence.. A bar near Station 3 had gravel up to 30 mm
15
•
I
[
..'•... :.
''''','
.'......
·l,.,j
FIGURE 5
mID % Revetments
III % Bank & Terrace
I3i % Bank
~ % Sackcrete
~ % Armorloc
~ % Concrete Ret Wall
13 % Rlprap
Bank PhysicalDiablo Avenue
ProjectBlvd to
ControlRedwood
FloodFrom
4%
2% 2%
% Bank Types per ength of Channelfor both Banks
Channel reach length = 3460'
(most of this reach is influenced by both tidal and terrestrial flow)
NovatoConditions
;',0""",.... 0, % Total Revetment Types for Both BanksChannel reach length = 3460'
~J
~J
"J~;~
uJ'''')
i'.';,
,J,J~]" .
'J':...
~J
; "I
; ,.,
-J
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J
Channel Bed Cores from Novato Creek Flood Control Project5/27/97
Sta 163+50'
#7
downstream at railroad bridge
•
FIGURE 6
Sta 843+10'
#6.','.',. .. ,. ,'.. ., .. .. .. .. .. .. .. ......... .. .. .. .. .. .. .. .. .. .. .. .. .. ......... .. .. .. .. ., .. .. .. .. ......... .. .,'.',',........ ........, ......... .
Sta 637+55'
#5
., .......... ,.. ......... .'I',','. .. .:.:.:.:, '., ................................. , ....... '................... , ..:::::::' .. ' ... ........:.:.:.:................... '...... '., .... '...............,',',',.' .....
Sta 534+40'
#4
..... ......... ..' .
Sta 429+44'
#3
., .., .. .:.:.:.:::::::: 30rnn.'.'.',......., ..'.'.'..:.:.:.
Sta 323+85'
#2
lOrnn
K(Y
I Predominantly clay
[J,', Predominantly sand.:.:.:.:.
"::"':.... ..Predominantly gravel.... ..
....:...
~Organic detritus withsand and finer sizes
~ Organic detritus withsilt and finer sizes
I Compacted silts &and clays at top
of dredged surface
.. .. .......... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .......... .. .... .. .......... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. .... .. ..
Sta 219+30'
#1o
05 - --
1.0- - -
15 - - -
2.0- - -
2.5 - - -
4.0 - --
...--
upstream at Warner Creek
3.5. __
Q)Unl...:::JIII
"'0Q)
.t:l
Q)CCIII.r:;U
~].r:;Q.~ 3.0 - - -
surface
near Arroyo Avichi confluence. Both these tributaries have created alluvialfans, with gravel-sized sediment, at their NFCP confluence, Photos 19 and 22.
The significance of sand and larger gravel-sized sediment is that the source ofthis material is the upland watershed, not the tides. Tidally derived sedimentis not expected to be larger than fine silt to clay-sized. Figure 6 showsanother interesting stratum that is associated with organic debris, at corestations 5 '(34+40') and 6 (37+55'). At the latter stations, the mixture of
.organic debris and sand or finer sediment accounts for more than 45% of thevolume or bulk of each core. Much of the organic detritus was leaf litter frombay trees and deciduous riparian vegetation, such as willows.
At station 39+00', which is upstream of the Highway 101 Bridge, sedime~t ontop of hay bales that had been placed on top of the flood control banksexhibited a veneer of fme silt to clay sediment about 1" thick, Photo 11. It ispresumed that the hay bales were placed in November 1996. This gives adeposition rate on the Flood Control Channel banks of at least 1" in half ayear. It is not known if this can be extrapolated to 2" per year since the haybales had decomposed by the end of 1997. The source of the sediment maybe the suspended supply from both tidal and upland winter flood flows.
Since the NFCP had been dredged the winter before this study, core stations 2and 4 intersected the top of the dredge surface that had compacted silts and.clays. The surface of the dredged bed may have been very uneven such that
. the amount of deposition at these discrete points may be the minimumamount that occurred during 1 winter. The cores at station 8 (43+10') andstation 1 (63+50'), in Figure 6, show that mostly clay-sized sediment waspresent following the dredging and the 1997 winter flows. However, Photos 7and 8 show stratification of fine sand-sized sediment in 1996 dredge spoilsthat had been placed on the levees downstream of the railroad bridge. Thespoils indicate that sand from terrestrial sources had been transported anddeposited within the flood control channel beyond the extent of railroadbridge.
Figures 7a, band c show the distribution of sediment in cores that were takenin October 1997, five months after the first set of cores. This later coring wasdone to determine the contribution of sediments from tides alone, whenterrestrial flows would be minimal and not transporting bedload or significantsuspended sediment. An attempt was made to take three cores atapproximately the same distance stations but along a transect across thechannel bed to better define the range of variation. In the downstreamreaches at core station 6 (37+55'), it was too difficult to wade across thechannel bed so only two cores were taken.
18
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I
,"" ~f
Channel Bed Cores from Novato Creek Flood Control Project
10/15/97
silt
gravel
clay
KEY
Predominantly
Predominantly
Predominantly sand
Predominantly
10mm
rt:"':........:.:.........~
-;:-........ ....A ..
:..:.:
I Silt with minor gravel
II
.... A.. A •.. .. ..A .. A
A .. ... .. ... .. .... .. .... A ..
• A •.. .. .... .. .... A .... .. ..•••••••••••••••
#10 RB
------
.. A A.. .. A
.. A A.. .. ..A A ..
.. .. AA A A
A .. .... .. A
• A A.. A A.. .. ..A .. A
• A AA .. .... A A
A A ..A .. ..
.. A A
• .. A.. . ..A .. A
A .. A.. .. .... .. A.. .. .... .. A
A .. •
lOmm
lZrrwn• A •· .. ..· .. ..· ..· .. .· .. ........
#8 LB
DownstreamSta 3 at 23+85'
#9 i~~~~------
32rrwn
ol-__~-----------
~- - - - - - - - - - - - - - - - - - -~- - - - - -
UpstreamSta 2 at 19+30'
#13 RB#11 LB #12 <i.O~~~~~....~..
..••••: 16mm :.:..:. on bar ::::::..A .... A" nearb\l ::::::
.. .. .. '. II',A .. .. • ••• ',
A ... ... • '. I,... .. .. . ...... • .. • •••• I....... ...... A .. '. I,
A .. .. • •••.. II> .. • •••........ ...... • .. '. I.A..... :.:... A • • •••... "" .. •I,'.. .. .. .' I'A.... ....A .. ... .. •••:..:..:. I::::.. #10 .. • II........... :.:.
A A AA A A
A A AA A A
A A AA A A
A A AA A A
A A AA A A
A A AA A A
A A AA A A
A A AA A A
A A AA A A
A A AA A A
A A AA A A
A A AA A A
A A AA A A
A A AA A A
A A AA A A
• A •.. A ..
A • A
• A A· ..· .. .• .. A· .. .• A AA • A.. A ..
• A ..A • A
• .. A· .... . ..• A •A • AA • ..
• A AA • ..
A A A
• A •· . .· .... . .• A A
1.0
0.5
2.0
1.5
2.5 .• - - - - - -
3.0
GlUClI~::::lIII
'"0Gl.c
Qjc:c:ClI
.c:u
~J2Gl.c
.c:...Q.Gl
'"0
...--
surface
'"
....
3.5 _ Gravel
4.0 DSample not capturedbut may containfine gravels
ICompacted silts 81clays, top ofdredged surface
frrwnIMaximLWP .Dilrticle 8fU
Figure 7A
I
Channel bed Cores from Novato Creek Flood Control Project
10/15/97
,
(,'" ~'
---------. -----~ - - - ------- - - --
--------------_.------------- ..KEY
~~_______I predomina"';ly clay
I Predominantly silt
-------- ~,'.: : : Predominantly gravel,',,',~
. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _~ Predominantly gravel
. ~
Sta 4 at 29+44'
#14 LB #15 (i
2.0 - - - - - - - - - - -
1.5 . - - - - - - - ~ - -
0.5 - - - - • - - - - -
2'i 1.0 - - - - - - - - - - J!!5til
1"1l
!I..at
surface 0 ----------- __
2.5 . - - - - - - - - - -
3.0 - - - - - - - - - - -
3.5----------------------.-------
OSample not capturedbut may include fine
gravel
~ Organic detritus with~ sand & finer sizes
~ Organic detritus with~ silt and finer sizes
I Compacted silts &clays, may be top of
dredged surface
1----
•........ 1"
4.0-----------------------------------------------------
FIGURE 7B
;'·..·'1
Channel Bed Cores from Novato Creek Flood Control Project
10/24/97
Organic detritus withsilt and finer sizes
Organic detritus withgravel and finer sizes
Sample not capturedbut may includefine gravel
Organic detritus withsand and finer sizes
rr;.::: Predominantly sand,',,',L:l..:.r""":'"..::: Predomiantly gravel
c..:..
I Silt with minor gravel
KEY
I Predomiantly clay
~ Predominantly silt
Downstream
Sta 6 at 37+55'
#19 LB #20 <i..
Upstream
Sta 5 at 34+40'# 16 LB # 17 <i.. # 18 RB
0.5---~........,
1.0 - - ~
2.0- - - -~...:..6..3
1.5 - - -
" .",,,,,,
3.0- - - - - • - - - ••1....--..--.-!"""""':
2.5· - - - - . - - - - . -
surface 0
" .';
3.5-----------------------------------------------------
40 ----------------------------------------------------.. FIGURE 7C
The three cores at core station 2 (19+30') show an insignificant veneer of siltat the top of the core and sand to gravel-sized sediment at the transect.Gravel up to 26 mm was observed. The voids in most of these cores mayhave been noncohesive, sands and gravels. Varying amounts of gravel werefound at core stations 2 through 6, with particle sizes up to 6 mm at the latterstation. Core stations 1, 7 and 8 were not recored. The cores at stations 5(34+40') and 6 (37+55') showed that the organic leaf litter and debrisaccounts for over 40% of the volume. Evidently, the detrital matter thatwashes downstream during the first significant winter flows substantiallybulk and contribute to filling of the tidal channel. When there was afunctional marsh system, before diking and reclamation, these rafts of organiclitter would have settled onto the ~arsh surface or channel banks, or theywould have been washed to the bay.
The coring indicates that the upper third of the flood control channel isdominated by sand and larger-sized particles from upland sources and thatfine grained tidal sediment probably amounts to less than 20% of themeasured sediment volume. From one third of the distance to more than halfthe length of the NFCP study reach, tidal sediment probably amounts to lessthan 50% of the total volume. Further downstream at the railroad bridge, finegrained silt and clay predominate the total volume, but it is not presentlypossible to determine the percentage of this sediment that is derived from.tides or that is reworked fme sediment derived from upland sources. Also, itis not presently clear if the veneer of tidal sediment that is deposited duringthe summer remains on the bed or is reworked during high winterdischarges, when bed shear stresses would be greater.
In March of the 1998 Water Year, after very high winter storm flows, LizLewis and other .MCFCWCD staff went to some of the same reported coringstations. They found sand and fme gravel-sized sediment downstream of therailroad bridge, with gravel up to the 6 mm size at the NWPRR Bridge. Thehigher peak flows of 1998 (3,194 cfs) were able to transport coarse-sizedsediment farther downstream than the preVious flows of 1997, (1,893 cfs).
Findings for Novato Creek...Upstream ot Qialllo Ayenue BridgeBank ConditionsThe lateral extent of eroding banks and revetment upstream of Diablo
. Avenue Bridge to Stafford Dam spillway was measured to determine theexisting conditions of the channel and terrace banks and to establish whetherbank erosion was a significant source of sediment supplied to the NFCP. Theraw data are compiled in the Novato Bank Data Table, Appendix A2. Figure 8shows three pie charts that represent channel bank condition and revetment
22
I
I
.."".~'
NovatoBank Physical Conditions
Combined Upstream of
Creekfor AllDiablo
StudyAvenue
ReachesBridge
BELOW BANKFULL HEIGHT9%
I'm % Eroding
..,Diablo to Stafford Rep
[ill! % Revetments
ABOVE AND BELOW BANKFULL HEIGHT
m Revetments
.' ~ ~...: ; .:.. ;", :
II Eroding
Diablo to Stafford RCP
FIGURE 8
I§llJ Concrete wall
types
Sackcrete
Riprap
~ Other11.1 %
Diablo to Stafford RCP
TYPES OF REVETMENTABOVE AND BELOW BANKFULL HEIGHT
11.1 %
type for the entire Novato Creek study reach to Stafford Dam. The top chartshows the percentage of eroding, stable and revetted banks below bankfull,
while the middle chart shows the percentage of these conditions when terracebanks are combined. For both pie charts, the percent revetment is the samebecause its vertical extent was not measured separately for bank and terrace.
The charts show that if just the bankfull banks are considered, 34% of thebank length has eroded more than 0.5', and 9% of the total length has beenrevetted. It is likely that some portion of that 9% was also eroding andsupplying sediment to the channel in the past before revetment. The middlechart shows that when the terrace banks are considered, a larger proportionis stable, reducing the total percentage of eroding channel length to 30%.These charts also show that only about 60% of the channel banks providenatural stable habitat. The bottom pie chart shows that the most Widely usedrevetment type is riprap, contributing 56% to the total.
Figure 9 shows a histogram representing the total distances, along 8 differentreaches, of eroding, revetted or natural banks below the approximate 5'bankfull level. These reaches are simply dermed by bridge crossings (DiabloAve., 7th St., Grant Ave., Simmons Lane, and Sutro Ave.) or significanttributary confluences (Bowman Creek and Las Dias Creek). This chart showsthat the amount of revetment decreases upstream, and that there is a slighttrend of more stable natural banks upstream of Simmons Lane Bridge. If alarge proportion of the revetted banks in the downstream area were erodingand supplying sediment prior to revetment, then downstream reaches havebeen even more significant sediment sources than at present.
Figure 10 shows pie charts representing the percentage of total length oferoding, revetted and stable banks below the bankfull level for each of sevenreaches. The charts indicate that eroding banks range from 22% of the totallength in the Simmons to Las Dias reach, to 40% in the Bowman reach. If mostof the revetted portions of the banks were once supplying sediment, then thebanks of 7th and Grant reaches have been the most significant sedimentsources, since less than 48% of their bank length is classified as stable. TheSimmons reach has the highest percentage of stable banks, 68%.
The abundance of bank erosion in the Novato Creek reach upstream ofBowman tributary is likely due to the immediate effects of the trapping ofbedload by the dam. Subsequent adjustments in channel geometry andgradient were caused by changes in sediment and water supply. Theabundance of eroding and revetted banks in the first three downstreamreaches may be due to grade adjustment that propagated upstream from
24
t; :•.':i~
I'"
l. I
Extent of Eroding and Revetted Banks Below Bankfull Height,for Both Right and Left Banks Along All Study Reaches
upstream of Diablo Ave Bridge
..... i··· ..r· .. j······!
li!1~ j i: : :
.....)..-1--29';.. ..:·)·: : : :
....: ; ;.
. . .~ : :
• ~ 'Taltal! : r~vetrl]le~t :~: ~r()tai: bl.)hi/: :r'dnk~o.
. , ··!r;·t:~·;;;;v"·i"·Tr.Ji'·\k'f i/W:"'j'" ·;.. ···-:- .. 1..
Tdtal, brQditl9 : ~arlk$ ~ !: : ibeiow ~ bankfull: : : : l...;.. ir .. ·(·.. ·, ..·.. ; ····:..··..:..·..I·....:··· ..r.... l......'....·'1'·
00 5000 10000 15000 20000 25000
t 1Distance (ft)
1 1 t S 1 t ta::l a::l.. a::l .a a::l ..Q EQ) l:D Q) ,- "'C Q) 't:> > s: .. > > I- ro« +J « ...J I- - 0
V> co «en en s::: "'Co..0 ..c +J s::: ro 0 0 E ... u
:0 +J s::: 0 £S +J .. £0:'"
CIS E CIS +J.~ 100. > ~ ;:0 C,,!) .§ en 0 (/) 0 ro
CIS +J(/) ...J Z a::l (/)
FIGURE 9
8000
6000
4000
2000
14000
en 12000..:l'
s:::ro
a::l
~ 10000r::a...genQ)100.~+JroQ)
u..o+JQ)Q)
u..
BankNovato
Physical Conditionsfor Individual
CreekBelow Bankfull
ReachesHeight
I-
1- ':,
Diablo to 7thChannel Length = 2446'
14%
Simmons to Las Dlas TribChannel Length = 2011'
7th to GrantChannel Length =2010'
6%
Las Dias Trlb to NovatoChannel Length = 3522'
Grant to SimmonsChannel Length =3167'
12%
Novato to SutroChannel Length = 2510'
lli@ 0/0 Revetments1% 2%
[jlJ .-
~ % Below Bankfull-:-.
Sutro to Bowman TribChannel Length = 6379'
Bowman to Stafford RCPChannel Length = 3927'
FIGURE 10
Bank PhysicalNovato
Conditions Abovefor Individual
Creekand BelowReaches
Bankfull Height
2%
"
Diablo to 7thChannel length = 2446'
4%
7th to GrantChannel length = 2010'
5%
Grant to SimmonsChannel length =3167'
Las Dlas Trlb to Novato Novato to SutroChannel length = 3522', bedrock banks = 1.6% Channel length = 2510'
Hillside erosion along right bank = 3%
12%0%
8%
4% 7%
6%
2%
Simmons to Las Dlas TribChannel length = 2011'Bedrock banks = 10.6%
,;I
'J
: .'
1% 1% 1% 2%IjJ % Revetments
5% 7%
"':. ::.,.
~ % Below Bankfull
.. % Above & BelowBankfull
Sutro to Bowman Trlb Bowman to Stafford RCPChannellenglh =6379, beci'od< tanks=1.8% Channellenglh =3927', beci'od< tanks =10.2%
Hillside erosion along right bank =2% Hillside erosion along right bank =12% 0/0 Above BankfullFIGURE 11
i .;
earlier channelization projects, revetments that had poor hydraulic designand thus exacerbated erosion on the opposite bank or at the edges of therevetment. Additionally, increased urban runoff is likely affecting the entirechannel. Even though the effect of the dam reduces peak flows, it alsoattenuates the length of time that moderately high flows on the recessionlimb of the hydrograph are able to erode channel banks. The naturalhydrograph would have a sharper peak but a more rapid drop on therecession limb. Thus, with the dam, there is more time for shear stresses thatare capable of causing erosion, to work on the banks.
Figure 11 shows the percentage of eroding banks on the terrace and bankfullbanks. The solid red areas represent where the combined vertical extent ofterrace and bankfull bank is eroding. Heavy stippled areas represent wherethe bankfull banks are eroding, and light stippling represents just the terracebank erosion. The reaches of 7th to Grant, Sutro, and Bowman all havecombined terrace and bankfull bank erosion that exceeds 25%, with the latteras high as 27%.
rosl0n ong ovato reeBankfull Erosion 11 511 cu vdsTerrace and Bankfull Erosion 17555 cu vdsTerrace Erosion 1105 cu ydsTOTAL 30171 cu vds
Point measurements were made of the amount of bank retreat along NovatoCreek. These raw data are in the Field Notes in Appendix Bl and in BankErosion Data Tables in Appendix A2. The maximum amount of bank retreatmeasured was 52' at station 233-91' (Watershed Map 6). If just the spotchecks are averaged, then an average value of bank retreat is about 5'. Sincethe spot measurements may have been skewed to measure the more severeerosion sites, a conservative estimate of 3.5' average bank retreat isestimated to roughly quantify the volume of sediment supplied to NovatoCreek from local bank erosion. The onset of the erosion could be assumed tobe no older than the oldest tree that has its roots exposed. The bankfull bankheight is estimated at an average of 5'. If the combined height of terrace andbankfull bank is generally 11' to 14', a conservative estimate of 11.5' can beused for the average height of the terrace and bankfull banks. Th~ terracebank average height would be about 6.5'. Estimated volumes of bank erosionare reported in the table below.
Table 4. Conservative Estimate Sediment Volume from BankE Al N C k
The channel bed is another source of sediment to the NFCP, particularly ifthere is abundant sediment stored as gravel bars. Bars above the mean bed
28
Type of BankNovato
RevetmentCreekfor Individual Reaches
...
...
...
L,·,
'"
I·
Diablo to 7thTotal revetment in this reach = 19%
14%
Simmons to Los Dlas TrlbTotal Revetment in this reach =14%
7%
3%
9%
7th to GrantTotal revetment in this reach =21%
12%
Las Dlas Trlb to NovatoTotal revetment in this reach =7%
0.5% 8%
2%
8%
Grant to SimmonsTotal revetment In this reach =18%
Novato to SutroTotal revetment in this reach =12%
...
:,.i,j
1(1D/-
Sutro to Bowman TrlbTotal revetment in this reach =1%
Bowman to Stafford RepTotal revetment in this reach =2%
0/0 cement wall0/0 rip rap0/0 Sacrete0/0 shop cart0/0 rock wall%l brick wall0/0 cement slabs0/0 steel pilings0/0 wood wallo,/~l Da.bions
FIGURE 12
" -;~
height were measured between Diablo and 7th St bridges to ascertain theminimum amount of sediment stored in the bed. This was a minimum estimate because actual depth of the bed could not be measured. The bar volumeamounted to about 500 cu yd. This is only about 33% of the total supplied bylong-term bank erosion in this reach, which is estimated at about 1,500 cuyds. If the 500 cu yds was spread over the length of this 4456'-long reach,on a 25' wide bed, then the average height would equal 0.12'. This value willbe compared to other tributary channels where bed storage estimates wereconducted. It was noted during the field reconnaissance that there wasabundant fme, sand-sized sediment throughout Novato Creek. The erosion ofthe local terrace banks, probably account for a high percentage of the fmessince the banks are mostly sand and finer sizes. Gravel banks were observedinfrequently. The bed exhibited little relief and it appeared aggraded atstation 5-34', coinciding with the maximum extent of the backwater thatcould be created by the top rail of the NWPRR Bridge during high peak flows.
Revetment and the percentage of different types used in Novato Creek, canalso be viewed on a reach basis as shown in Figure 12. Except for the Sutroreach, riprap is used more widely than any other revetment. Sackcrete andconcrete walls are the other most common bank structures. Erosion along theends and opposite banks of these revetments was often observed as indicatedby the Bank Condition Charts in Appendix H._ These graphs depict 1,OOO'-longreaches and show the distribution of eroding banks, revetment, pools anddebris jams. The insert maps on each chart correspond to the WatershedMaps in Appendix A These maps can be used as future tools for monitoringchange as well as assessing existing condition.
Canyon slopes, rather than terrace banks, are more frequently interceptedupstream of Sutro Avenue Bridge. Bedrock banks are relatively uncommon,amounting to less 3% of the overall length of channel banks. As noted inFigure 11, Las Dias and Bowman reaches have about 10% of their total banklength as bedrock, while Las Dias and Sutro reaches have less than 2%.Simmons reach has the highest percentage of stable banks, 68%. This may bedue to the fact that about 10% of its banks are bedrock and it is relatively faraway from the upstream impacts of the dam and the downstream impactsfrom the realignment of Novato Creek tidal reach and excessive urban runoffin the more concentrated urban zone.
Bed Condition Relative to Pools and WoodPool and woody debris characteristics upstream of Diablo Avenue Bridgewere measured to: 1) determine whether the bed was following the usualrelationships of pool/riffle ratios; 2) to gain insight into the causes of whatwas forming the pools which is of interest to the MCFCWCD as habitat. The
30
•
raw data are located in the PoolslWood Table and Bank Summ,ary Table inAppendix A2.
In natural channels there is an expected relationship between the number ofpools and their spacing relative to bankfull width. In general, there should bea pool for a every 5-7 channel widths. Excessive sediment deposition cancontribute to the loss of pools and thus pool frequency measurements can bemade to assess sediment transport capacity and channel condition. Channelcurvature alone will usually produce the expected ratio. The estimatedaverage bankfull width for the Diablo to Stafford reach is 30'. Thus, poolswould be predicted to occur at a minimum, every 150' - 210'. . The tablebelow re.ports the spacing of pools greater than l' for the seven differentreaches.
I
,.l
." ....
" ....
\.0<0....
,.,,"
. .. . .
Location Total Distance (ft) Number of Pools Pool Spacin.2 (ft) . . ,
Diablo to 7th 2446 12 2047th to Grant 2010 19 107Grant to Simmons 3167 23 137Simmons to Las Dias 2011 9 223Las Dias to Novato 3522 30 117Novato to Sutro 25160 29 87Sutro to Bowman 6379 65 98Bowman to Stafford 3927 28 140Diablo to Stafford 25978 215 121 -
Table 5. Pool Distribution for Individual Reaches of Novato Creek .
Pool spacing for Novato Creek ranges from 1 pool every 87 feet in the Novatoto Sutro Reach, to 223' in the Las Dias reach. The latter reach has 1 pool perevery 7.4 channel widths and appeared to have more sediment stored inlarge high gravel bars. The bars appeared to be relatively mobile (loosegravels and little establishment of vegetation) and could contribute tobedload transport to downstream reaches. Except for this latter r~ach andthe Diablo to 7th reach, pool spacing is more frequent than every 5 channelwidths. relative to the discharge of the channel were observed to be quitesmall.
The three pie charts shown in Figure 13 show the percentage of differentcauses of pools, the percentage of tree types that have contributed to largewoody debris (LWO) within the channel banks, and the characteristics of thedebris jams. The top chart shows that of the 215 pools in the entire Diablo toStafford reach, 44% of the pools are formed by wood (i.e., LWO, roots, treetrunks), 33% are fonned by natural features (i.e., bends, bars, bedrock), and21% are formed by man made structures (i.e., concrete abutments, riprap)that inadvertently cause bed scour. . :1
31 :i'i'~
~
DEBRIS JAM CHARACTERISTICS
Diablo to Stafford RCPOf the total 84 pieces of LWD, 44 are baytrees that have fallen from terrace banks.
FIGURE 13
o~ Bay Tree
IS] Oak Tree
o
IIIlll Other (~ bedrock,ben, boljders)
EJ IVIan-made structures(bridges, concrete, ripraptransported from bankstabilization projects)
IlIlll Wood (tree trunks, roots,\iI/cody debris, debris jams)
III Undetermineej
o ,",:c
CI Partly blown-out
III Across channel bed
Debris Characteristicsof Diablo Ave Bridge
2%
2% 6%
Diablo to Stafford RCPTotal # of pools = 215,
Average pool spacing =121'
Diablo to Stafford RCPOf the total 21 debris jams, 18 occur
upstream of Sutra Ave Bridge
Pool and WoodyReaches Upstream
CreekStudy
CAUSES OF POOLS GREATERTHAN l' DEEP
TYPES OF TREES COUNTED AS LARGE WOODY DEBRISBELOW BANKFULL HEIGHT
Novatofor All
J
J
)
]
j
~1
~J
.J~]
..J~,J
v]
c,]
..]
,J
J.J,]
]..
..
::.':':
"'
,-
Wood is of interest to sediment studies because it can increase sedimentstorage in gravel bars behind the wood, it can increase the number of poolseven if a channel is aggrading, it can force flow into opposing channel banksand induce bank erosion, it can trap huge quantities of sediment behinddebris jams and change local channel gradient and sediment transport, and itcan suddenly release slugs of sediment downstream when debris jams areblown out. The recruitment of wood to the stream is also of interest becauseit may be associated with inputs of sediment from landslides or bank collapse.LWD and woody debris jams are natural features to a proper functioningstream
The middle pie chart in Figure 13 shows that of the 84 pieces of LWO thatwere tallied, 53% found in the Diablo to Stafford reach are formed by baytrees that have uprooted and fallen into the channel. The actual number ofbay trees is 44. Willow trees represent about 39% of the LWD. Interestinglyboth tree species can withstand substantial disturbance to the roots such thatsome can remain viable after they fall. Nevertheless, their collapse into thechannel can represent the loss of a riparian resource, especially if they fallwithin flood control jurisdiction because their trunks will most likely be cutfor flood control purposes.
The debris jam characteristics shown in the lower pie chart of Figure 13 showthat of the 21 debris jams that have fanned upstream of Diablo Bridge, 18 ofthem occur upstream of Sutro Ave and only 33% of these debris jams extendacross the channel. The rest are either partially or entirely blown outremnants. The Sutro pie chart in Figure 10 showed that this reach, and theupstream Bowman reach, which is just downstream of Stafford Dam, both hadvery high percentages of bank erosion, 38% to 40% respectively.
The lack of debris jams downstream of Sutro bridge is demonstrated in Figure14. These downstream reaches reflect the MCFCWCD management activitiesof wood removal. If the Bowman and Sutro reaches are viewed in thehistogram, then the impacts of the dam become more apparent upon quantityof trees and debris jams in the upstream reaches. The excessive bank erosionin these reaches has lead to the subsequent loss of trees and the positive feedback loop that increases bank erosion even more after the trees fall and bankcohesion is diminished. The segment of channel upstream of Sutro AvenueBridge provides the highest concentration of bank derived sediment, asdemonstrated in Figure 11, that showed the highest percentage of combinedbank and terrace erosion.
33
~~ VlQ)I...~
<!' +oJro
~"l';;Q)
u........... 0I...
..'I~~Q)
..0E
".~
Z
.,-;i!
It
~:3.~
I!'
.'l-~i
'!l
,;:;;;i
11
.~("~
.~~
,,;
Quantity of Pools > l' Deep and Large Woody Debris,Along Novato Creek
from Diablo Ave Bridge to Stafford Dam
• # debris jams
100II "# trees cross channel
, :i\: r ~ j I r·:':">' ,;
!II # of Pools
80
60
40
20
00 5000 10000 15000 20000 25000
tDistance (ft)
f t t t 1 t t tco ..0
I... I... co ..0 ·C EQ) co co ·C "'0 Q) I- roc I- >> +oJ -l -l > 0« (/)
.... co « cc Vl -oQ..ro Vl ro ro..Q .s::: I...
cis 0 0 E I...U
+oJ <.!J 0 -+-J I... 00:::..0 "- E ro +oJ ~ ........~ ~
.......E Vl > (/) 0 ro
0 ro 0 co +oJ
(/)-l - Z (/)
FIGURE 14
The pool forming causes are viewed on an individual reach basis (Figure 15)Sutro and Bowman reaches have over 50% of their pools formed by wood. Adiscussion of pools is not undertaken in detail since this a report on sedimentsources and supply, not of fish habitat. It is notable, however, that pools fillin when sediment supply exceeds transport capacity or unless there issufficient scour caused by flow obstructions such as LWD. An interesting noteis that, the Diablo to 7th reach shows that it doesn't have any pools that areformed by natural features such as bends or bars. In fact 58% of its pools areformed inadvertently by man-made structures. One of the commonobservations in this reach was that many of the pools were formed by riprapthat had fallen out of place from the banks or that abutted into the bed. The42% of pools that were formed by wood in this reach were mostly scour poolsthat formed beneath large bay trees with their roots exposed by bankerosion. This is true in many of the other reaches as well.
Figure 16 shows, on a reach basis, the percentage of different types of treesthat have already been uprooted and fallen into the channel bed. Althoughmost of the LWD is bay trees from the Sutro and Bowman reaches of NovatoCreek, the Las Dias Reach also had a significant input of bays. The otherreaches have most of their woody debris supplied by willows. Typically, thewillows are growing much lower near the bankfull elevation, whereas most ofthe bay trees in Novato Creek grow on terrace banks. Bay trees have beenobserved to grow at the bankfull elevation, which may imply that the largebay trees growing at or near the top of the terrace banks may haveestablished when it was a functional floodplain.
Bankfull GeometryAccording to regional curves (Leopold, 1994) which were developed for anaverage of 30" mean annual rainfall, a drainage area of 17.6 sq mi in the BayArea would have bankfull width (Wbf) equal to 46', a mean bankfull depth(Dbf) equal to 3.3', and cross sectional area at bankfull (CAbf) equal to 152 sqft. The drainage area above Stafford Dam is 8.4 sq mi. Therefore, when thereis no flow over Stafford Dam, only 9.2 sq mi of area drains to the NovatoCreek at the USGS gage site. Flow over the spillway usually lasts about onemonth, between January and February (Liz Lewis, verbal communication).The predicted bankfull geometry from the regional curve for the smallerdrainage area below the reservoir is Wbf = 37', Dbf2.6', and CAbf96 sq ft.
Field indicators of bankfull stage in Novato Creek are not definite. This isbecause ongoing adjustments in channel geometry have been caused bychanges in water and sediment supply from the construction of Stafford Dam,urbanization below the dam, increased drainage density and bank erosion,bed incision, and changes in channel gradient due to realignment and
35
Causes of PoolsNovato
Greater ThanCreek
l' Deep for Individual Reaches
Diablo to 7thTotal # of pools = 12
Average pool spacing = 204'
Simmons to Los Dlas TrlbTotal # of pools = 9
Average pool spacing = 223'
1% 6%
Sutro to Bowman TrlbTotal # of pools = 65
Average pool spacing = 9B'
7th to GrantTotal # of pools = 19
Average pool spacing = 111'
Las Dlas Trlb to NovatoTotal # of pools = 30
Average pool spacing = 117'
3% 7%
Bowman to Stafford RepTotal # of pools = 28,
Average pool spacing = 140'
Grant to SimmonsTotal # of pools = 23
Average pool spacing =143'
7%
Novato to SutroTotal # of pools = 29
Average pool spacing =B6'
0/0 man-made structures(bridges, cetnen~ rip raptransported from bankstabilization projects)
III % wood (tree trunks, rools,woody debris, debris jams)
Illlill C¥o other (bends, bedrock,bars, boulders)
undetermined
FIGURE 15
NovatoTypes of Trees Counted as
Below Bankfull Height
CreekLarge Woodyfor Individual
Debris (LWD)Reaches
14%
100%
Grant to GlmmonsTotal # of LWD = 1
7th to GrantTotal # of LWD = 0
Diablo to 7thTotal # of LWD =7
100%
Novato to SutroTotal # of LWD = 3
Los Dlas Trlb to NovatoTotal # of LWD = 6
Simmons to Los Dlas TrlbTotal # of LWD = 1
5%5% 7% D
~ Oak Tree
,";i .','
mJ Bay Tree
DBowman to Stafford Rep
Totallfof LWD = 28Sutro to Bowman Trlb
Total # of LWD = 38
channelization. Stability is needed to produce identifiable bankfull features.Based upon occasional spot measurements of bankfull width in the field and afew cross-sectional surveys, see Figures 17a-c, Novato Creek does not fit theexpected bankfull geometry of 46' wide and 3.3' deep. The average bankfull·width estimated for the entire reach is about 30'. It ranges from 22' to 57' .
The cross sections in Figure 17 were surveyed to show a range of variation inNovato Creek. The Cross Section Stations are also located on the WatershedMaps in Appendix A. The cross section at Station16+00' was surveyed toshow the typical channel geometry of a straight reach in the lower portion ofNovato Creek. Cross Section Station 212-15' was chosen because it was one ofthe few reaches that actually appeared to have a floodplain. Here the Wbf isabout 48', close to the predicted value of 46' from Leopold's regional curve.This site is shown in Photos 256-266, but the floodplain is hidden from viewby vegetation. Cross Section Station 214-90' was chosen because it hadsignificant bank and terrace erosion and substantial gravel bars, See Photo273. Cross Section Station 216-46', Photo 275 was chosen because it was justupstream of the latter station and probably represented the previousgeometry. It shows a Wbf of about 28', whereas the lower site has a Wbf of57'. The Cross Section Station 238-46' was surveyed to see if there was anysubstantial change in cross sectional area above Bowman Creek. The cross.sectional area was 114 sq ft as opposed to 310 sq ft at Cross Section Station16-00'. The Cross Section Data for the surveys are located in Appendix A2.
. An initial attempt was made to identify bankfull stage in these graphs. Thered arrows pointing to the right show the estimated maximum height ofbankfull. The thin red line below the red arrow shows a low bank observedin the field. What this low bank corresponds to is not known, but it is abovethe summer base flow level. The cross sectional area tends to be less than thepredicted value from the regional curves for just the drainage area below thedam, that excludes flow from further upstream.
These cross sections give a general impression about the form of the terraceand bankfull banks. Often they are nearly vertical and not distinct from eachother. Indeed, in many of the reaches of Novato Creek, if there is bankerosion of the bankfull bank, the terrace bank becomes destabilized as well.But in many areas the top fourth of the terrace bank overhangs the lowerportion because it is held together by tree roots, Photo 38 and 235 forexample. Many trees are precipitously clinging to the terrace banks.
Rosgen ClassificationDuring the field reconnaissance Novato Creek was casually categorized by itsRosgen classification (Rosgen, 1986). Since there wasn't a base map available
38
Cross Section at 16-00' Novato Creek
14.00
12.00,......:t::'-"" 10.00....J::.QlQJ
8.000::r:QJ>
'';::;6.000111
Q)0:::
4.000
2.000
Field measured low bank cross sectional area = 65 ft2
Terrace cross sectional area = 310 ft2······\·······l..····\·······,······\·······,······\·······,······,······v······,······ ·······.······..······.j ; '" ..
: : : : : I : : : : : : : : : : : : : :
'T'jlj]!!!i;[·f:][ij··~:I·:111:: ::::::::::: t : : : : :
::::::F:::F:>::::E::::F:::F:::F:::F:::i .::::F::I::::T:::E::::F::E::::F::E::::F::I::::J......1. L..... . L ~ J L i ; ! L L ! l i i L L i J
::::::L::+::::l<:+:::::l:::::+:::::L::+:::::::::L::f::::~.:::::I:::::t:::f::~!~~:t:~:l~::t:~~f...... : ~ : ~ : .:. : ..:. .:. : .:. : .:. : .:. : .:. : .:...... i ~ l.. ..~ L i L ~...... . 1 L 1 i 1. i 1 L 1 L j...... i· ·.~ i.·. ..i··· i ; i ·..·;·.·... . i .. ·· ..; i ·; ~ i ~ i······t i ~
: : : : : : :: :::::::::::...... ~ : -:..... ·····7······:······7······:······~······:······7······: ~ : ~
·~.j~~:::T~~j~~~: ..:::::::l:::j~~~:~J:~~·T~~·:.:~:~L~~J":~~l~::~t~d~~~J~~:~:~L~~I:~~~~LJ~~~]· ~ ~ i·······~ ~..... ." }.. . + ! t·· ! + ! t· !'" + ··!······1...... ~·······r······1·······t···· .. ~ i······: .~ t······~· ·····t······;······t······~······t······i······t······;······1
::::::L::::I:::::r::::I::::I::::j:::::I:::::.~ :~::::::r::::I:::::r::::J::::::r::::I:::::r:::::I:::::r::::::L:::]· L ~ 1. i L 1 i .i i 1 1. 1 i L f. i i i i 1· i ; i ~ i ; i i i ~ ; ~ i ~ 1...•..~ i i I ·· ~
: : : . : : : . . . : . : : . : : : : :
o 20 40Distance (ft)
60 80
Cross Section at 212-15' Novato CreekField measured low bank cross sectional area = 64 ft2
Terrace cross sectional area = 725 ft2
14.00
12.00,-....:t::'-"" 10.00....J::.QlQJ
8.000::r:QJ.~....
6.000111Q)0:::
4.000
2.000
o 20 40Distance (ft)
60 f·IGURE 17A
Cross Section at 21 4-90' Novato Creek
14.00
12.00,.....,~'-" 10.00+-'.t:Cl0Qj
80000:r:Q)
>0;:;6.000"'"'Qj
~
4.000
2.000
Field measured low bank cross sectional area = 57 feTerrace cross sectional area = 577 fe
f,!;[-J:jJ jJ III Ii r:I"jII-.tl I
:~~:~1~:J~~~~: ::~~~~LJ::·~:I~::J::::t:::::::::::~:::::L::::t::::::!::::J~~:J.:::~L~~:L~~:L~~:Lj......:...•...~ ; i ·.. : ···c·······~······i······o(o······ .f. •..••• j •••••. ~ ••••.• i ~ i.·..··i.· ..·.. i ~...... ~ t t ••••~ ••.••• i..·.. t •••••• i ~ i i i i i.. ···.~ ··; i ;· ~ i ~
::::::1:::::t:::t :::::::::1::::::1::::::I:::::::I::::::I:::::t::::I:::::t::::I:::::t:::t:::t:::t::::L::t::::J......1 ;.•.... i i J t i. t l L L l. i l i 1. L l i l....·.i.· ; i ~ : ; i· ; ; ~ i ~ i.·····~ i······~ ; i ; ~. . : . : . : : : : : : : . : . . . : :
o 20 40Distance (ft)
60 80
Cross Section at 216-46' Novato CreekField measured low bank cross sectional area = 50 ft2
Terrace cross sectional area = 257 ft2
14.00
, 2.00,.....,~'-" 10.00+-'.c.QlQ)
8.000:r:Q)
>0;:;6.000"'"'Qj
~
4.000
2.000
...... , ,. , , \ , \ , ··1······ ·····1 ··'····· ..1······ ······/ ..·····.· .. ····1-····· ..·······1·· ..··': : : : : : : : : : : : : : : : : : : :
::~±~~·r~:j:::~:~L~j:~·::T:::~:[~·:LJ~~:~L~:r~::T:::f::~:LJ:.:::T:~J::~~~L:J:~j
11111Itl~IIIIIII!111......~...... ······1·· '" ..~ : ~ ~...... .....•......~ J 01· •••• 0•••••• ·I······.······~······-1- ••••• •1 ~
l;ijj•••••i••··.l·•••j.l.ij·•••••lrJ;j]j~mllll~:: ::: t:::::~i ::~: t:::::j:::::: ~:::::::r::::::: .: ::::t::::::!::::::t:: :::: i::::::1:: ::~:!::::: :1::::::!::::::t: :::::f::::::1::::::!:::::j
:~::~~tJ::.·:t:::T:::T::::F ·y~:J~:J:::~~:LJ:~:J::::~r::~r~J:~~~~~L~J:::l:::~r::J: : I : : : : : : : : : : : : : : : : :
!]tfiilillillillilil.·..··~·······~······~······1······ i····· ·1······~····· ..~ ··r······f·· t······+ ~ + ~ + ~ + ~ '1
o 20 40Distance (ft)
60 80FIGURE 17B
Cross Section at 238-46' Novato Creek
14.00
12.00,-...,
.:t:........10.00....
..c
.21(I)
8.000:::c(I)
.~....6.000III
Q)cc
4.000
2.000
Field measured low bank cross sectional area = 38fe
Terrace cross sectional area = 307 ft2
................, \ / , , , , , ···,······ ..·······,······v······,······..
.. ~ ~ i··· ~ i··· ..-~ i··· ; i··· ~..- i······~ i······+_ i······~ u .;••••••+ ~.._ ~
::::::t:J::::t:::t:::t::t:::t::::t::t::::t:::J:::J::~t:t~t:J::td:::::t::j.. ~ ~ ~ ~ i ; i i i ~ i..... . i ~.···.·i ~ i ~ i ~
::::::;. ···::~::::::j:::::::i::::::j::::::l::::::l:::::j::::::I::::::i:~~:~:!··· ..:t~:~:::!:::::~t~:::::I::::::t::::::!::::::t::::::l:: ::::i......1.... : :. .1 :. 1 :. .:. :. .:..... . l !. l L l : l. ~ ~
......i L l i l L.. i i. L.... . L i. L L.. L .L L L. i
......l....... ...i i i J L i ~ ~ i .i i L i ! i ~ i j
:::::+::::1:..··:)::::::1::::::)::::::1::::::):::::::[::::::;::::::L .t:::::L::t:::::!::::::l~::1::~~h:~~:~I::::~r2: : : : : : : : : : : : : : : : : : : :
::::::F:::E::.··::::T:::::F:::1::::I::::E::::[::::+·.::::!::::::E:::E::::E:::f::::F::E::::E::::!::::::!...... ~ "'1' r····. .. "T ••····r..·": :...... . ~ + ~ ·f·· ~ + ~ + ·~······i
::::J::::l:::::LJ::::::t:::::i::::::::::::t::::E:::' :::::l:::::L:::L::::L::L::::LJ::::::L::::I:::J...... i. ······i ; ~ i ~ i· · i.. .+ i ~ ; ~ ; ~_ ; .i, ••••.. i J
~ll!l:!J~[-j!l~tli;!~rIJ~J~I;~lo 20 40
Distance (ft)60 80
FIGURE 17C
or information on slope, a rigorous delineation was not undertaken. Ingeneral, much of Novato Creek fits into the G4 and F4 classification with someoccurrences of the B4 class in the Sutro reach, and a small segment of D4 classin the Bowman reach. For a graphic example of the Rosgen Classificationscheme see Rosgen Classification Key A and B, Appendix B4.
Rosgen (1997) has described the evolution of entrenched channels throughhis stream classification system._ The central tendency of the incising,entrenched G4 stream type is to have a floodplain, a sinuous channel, and alower gradient. It will continue to erode its bed and banks in order toincrease its meander width (belt width). As lateral extension proceeds, thestream changes morphology from a G4 to a F4 stream type, which is stillentrenched, but has a higher width/depth ratio and has ceased to incise.Instead, it continues to erode its banks. When the belt width is sufficientlywide, a new channel is incised into the bed of the F4 stream, making theprevious bed the new floodplain of a C4 type channel. Rosgen's graphicrepresentation of this evolution is located in The Channel Adjustments Figurein Appendix B4.
The cross sections in Figure 17 reflect some of the Rosgen classes shown inTable 6.
Table 6. Rosgen Classification CharacteristicsCross Rosgen
Section StreamDistance ClassStation16-00 G4c
212-15 B4c (?)
214-90 F4216-46 G4238-46 84(7)
It is notable that the channel geometry in the lower half of the Diablo to 7threach almost fits the geometry for an E-type channel because twice themaximum bankfull depth is barely contained within the terrace banks. If thechannel aggraded slightly, its entrenchment ratio would change and thechannel would become an E-type channel. The Rosgen Classification suggeststhat this portion of Novato Creek was, perhaps, an E4 channel that hasentrenched, thereby initiating a sequence of bank erosion and bed incisioncharacteristic of a G-type channel. The channel within the tidal reaches,before man's alterations, were E-type channels.
Comparison to Earlier Photography and Channel Bed Incision
42
The comparisons to the 1987 Stueber-Stroeh Associates' photographs, takenbetween Grant Avenue Bridge and Novato Blvd Bridge, show a tendency ofchannel bed incision over a ten year period. The table below gives the photonumbers in Album I. A few of the earlier photographs were taken by staff ofthe MCFCWCD. The original numbering system for the Strueber-Stroeh photoscan be found at the top of the "xerox" photograph in Album I and their maplocation, as shown in the Stuber-Stroeh report, can be found in Appendix M.For the older photos, station distances are very rough approximations andwere estimated from the Watershed Maps, AppencUx At. Rephotography of .the sites was performed to compare changes over the last ten years.
h CT bl 7 R h ta e . epJ 0 oj!rap. IY ompartSonsAlbum Photo Stuber- Roughly Measured Ht Incision Est. Notes# Sroeh estimated Apparent amount
Photo # Sta dlst (ft) (ft)
53-54 2 45-50 no 056-57 3 45-80 2' root to thwR yes 1.558-59 4 46-50 3.2' root to thWI! yes 0.5-1.061-62 5 47-50 yes 7 bar has shifted65-66 6 49-00 6.8' root to thwR yes 0.5-1.068-69 7 50-SO yes 0.5 bar shifted & less
rlprap73-74 8 51-80 7 ? LB bars77-78 9 54-00 1.4' top of slab 7 0-0.3 -
to thwR79-80 10 55-50 A. 1.8' edge no 0
cone. to thwg11- 2.2' top ofledge to thwgc. 2.3' top ofledl!e to thWI!
81-82 11 57-00 3.5' saekerete yes 7 more saekcretefoottnR to thwR
83-84 12 58-00 3.5"base of 7 0-0.3trunk to thWI!
85-86 13 59-40 1.7' trunk base yes 0.3-0.5 more roots exposedto thwg on bar & tree
slumoed Into stream87-88 14 60-50 A. 2.8' root to 7 7
bedB. 3.2' root 'tothwgC. 0.55'= root tobed
(continued)
43
89-90 16 62-80 no 0
91-92 15 64-50 A. 7.5' = bend in yes 2.5 inroot to thwg tribB.4.7' = root toNC thwg & 2.5' 0.3-0.5roots to Oib bed inC. 3.6·... ledge to NovatotbWR Creek
94-95 17 66-00 A. 0.5' '" root to yes 0.1 exposed roots on barbarB. 3.4' ... trunkbase to tbwR
97-98 18 66-00 2.5' = break in 7 0-0.3 bar missingslope to thwR
99-100 19 70-00 1.9' = 7th row of 7 7sackcrete to thwR
101-102 20 70-60 1.3' = ledge of 7 0-0.3 exposed rootsconcrete to thwR
106-107 21 72-70 3.1' =root to thw2 yes 0.3108-110 22 73-50 5.1' ...root to thwg yes 0.5 exposed roots, tree
has fallen112-113 23 75-30 yes 0.3-0.5 low bank forming &
exposed roots115-116 24 76-50 2' = root to top of yes 0.5 bar missing, more
bar capacity118-119 25 77-40 4.2' = ? ? 4.2' bank loss @ B,
root to thw2 behind tree trUnk120-121 77-68 yes ?122-123 26 79-50 A. 1.5' = top of yes 0.3
rock to bedB. 1.3' = base offence to bed
126-128 27 82-40 A. 2' =root to bed yes 0.3-0.5 bank more definedB. 2' =trunk baseto bed
133-131 28 88-00 4.8' =Toot to bed yes 0.5 bank erosion == 8.2'135-139 29 91-00 A. 2' = top of ? 7
grouted rock tothwgB. 2.5' = bdrk tothWl!
140-142 30 92-80 4.5' = base of rip ? ? riprap apronrap proRressiYelv eroded
143-144a 31 93-00 ? 7 some loss of rip rap145-146 32 93-28 2.8' = edge of ? ?
boulder to bed
44
147-148 33 95-00 A. 1.9' ... top of yes 0.6can to bed 0.8B. 2.1' .. top of 1.1can to bedC. 2.1 ... top ofanron to bed
149-151 34 99-00 4.8' ... top of wood 7 7to thw2
156-158 0.5 Incision since 1971159-160 35 107-25 2' .. bottom of yes 0.5
eab-blon to bed164-165 1978166-167 36 113-50 1.2' .. edge ofcmt 7 slabs have sUpped
tothWIl168-170 ves 2nd slab has sHnoed172-173 37 116-00 yes 0.3-0.5 tree collansed 1996175-177 38 117-30 yes 0.3-0.5 1974 increased LB
bed erosion171-182 1973-1974183-184 39 117-30 0.9' ID base edge yes 0.3
sand bal! to thWI!186-188 42 120-00 2' .. base comer 7 7
rock to thWI!191-192 43 121-00 10.2' ... top of 7 7 bank erosion & tree
terrace to thWIl collanse44 122-50 3.8' .. top of root yes 0.5 more bank erosion
to thWl!45 125-50 A. 5.2' .. top 7 ?
bdrk to bedB. 2.7' .. base oftrunk to thWI!
46 127-50 A. 12.7' -terrace ? ?tothwgB.I0.8' ... trunkbase to thWl!
47 128-50 1.7' ... bottom of 7 7fence to thWl!
48 131-00 2' ... top of pipe 7 7to thWl!
The average for 31 values of incision reported in Table 7 equals 0.42' in tenyears. If the unknown amounts are considered to have no incision, then for49 values the average incision equals 0.26' in ten years. The average of boththese values gives 0.034' per year.
To account for this incision it may be valuable to consider the impacts of therealignment of the tidal reach that is estimated to have occurred about 1925.Roughly 1,750' of channel length was removed, Figure 2.' If the channel
45
CONIOUR INlERVAL 40 FEEl .DOllED lIHES REPR£S£NT 10 FOOT CONTOURS
NATIONAL GEOO£TIC VERTICAL DATUM Of 1929DEPTH CURVES IN n:U-DA1UM IS MEAN LOWER lOW WAY TR
lKt ~T1OHSHIP B£lW((t4 THE two QIl'fUMS IS YAAtA8l(SHORELINE $HOWH REflRES£K1'S THE APPRQXllU-f[ tnt[ Of lOGH W/AT£R
TIl[ fII[AH IWfC( or TID£. IS~ml s f££T. _-----.~....-:--.:-:-..:---.-f- -~.~.~ ..:.;.=.- ••••-
I'
.,.-·~1
'" I, i101." .
-c
i'
\., .31,
I "
-lj.i( t! ).
:/'
.r;:1,
i:-'
;.
, f
. \"
,.,
.)
"
'000 0H H H
IE+3
'000
,F3
0,
gradient before channelization in the mid 1920's is assumed to be about0.00077, which is a pre-channelization slope measured from the 1983channel profile of Camp Dresser and McKee, then the realigned channel wouldhave to adjust to a drop in elevation of at least 2.2'. Such a drop could haveinitiated a head cut, causing the channel to incise headward toward theupstream. Interestingly, if downcutting of 2.2' is spread over a 72 yearperiod from 1925 to 1997, it would occur at an average rate of 0.031' peryear, similar to the estimated rate from the photos.
Reading Trees and Rates ofIncisionAnother way to estimate rates of incIsion is to measure the trunk/roottransition height (relative to bed or terrace) and DBH of some of the oldertrees growing on the channel banks. The data are located in the Tree DataTable in Appendix A2. Certain trees still need to be cored to establish theirmaximum age, in order to complete this aspect of the analysis. A verytentative discussion of potential incision rates established by analysis of thevegetation is located in Appendix BS. The table below was derived from thediscussions in Appendix BS. It is important to keep in mind that incisionrates are averaged over time, while actual incision may be pulsed byindividual storms and punctuated by channel disturbance.
Table 8. Potential Rates of Incision and Associated Yearsfl'0 nltlal Instability
Distance Station Photo # Time Span Possible Year Roughly est.ift) Growth Beean Rate (ft/vear)
7-66 33 long-term 1886 0.034recent 1949
33-65 46a&46b mid term 1925 0.03677-68 117 recent 1949 0.034101-51 154-155 long-term 1873 0.034
recent 1952 0.034103-19 156 lone-term 1850 0.033103-35 none IOnlz-term 1900 "0.04103-69 ISS lone-term 1859 0.030115-00 171 long-term 1888 or 0.034
1835 0.034151-24 217 recent 1976 ..0.045162-00 225 recent 1952 or 1976? 0.059 or 0.045 ?198-00 251 lone-term 1835 0.034202-90 255 long-term 1835 0.034206-30 206 lone-term 1835 0.046209-45 261 long-term 1835 0.041251-47 297 recent 1952 0.046
46
The reported rates are considered conservative estimates that relied upon theolder range of potential tree ages, The estimated rates of erosion show thatlong-term and recent rates of downcutting are higher upstream thandownstream. This may be actual or may represent the fact that thedownstream has subsequently aggraded. The estimated years that incisionwas initiated show two distinct categories. One that ranges around the middleof last century, correlating to the onset of grazing and settlement of thewatershed, and the other around the middle of this century, correlated to theconstruction of Stafford Dam. These estimates may be revised, if tree datingis performed.
Comparison to Previous StudiesSix cross sections installed in the Diablo to Grant reach in 1985 by theMCFCWCD were resurveyed by staff during 1998. The cross sections arelocated in AppendJx A3. The rate of downcutting for these sections wasdetermined to be 0.13' per year (verbal communication from Uz Lewis),almost 4 times more than the estimated amount from the rephotographyanalysis that spanned the reaches from Grant Ave Bridge to Novato BlvdBridge. If this rate was applied to the Diablo and 7th St reaches the channelwould have incised 9.5' in the last 73 years. Perhaps the higher ratedownstream for the ten year period reflects some influence of dredging andchannelization.
In 1986 Prunuske Chatham described and documented sediment sources bywalking portions of Warner Creek and Arroyo Avichi, and the main stemNovato Creek between Grant Ave and Stafford Dam. They quantified thelength of bank erosion per length of channel (see Table 9) and determinedthat the ratio of stream bank failure to channel length was 1 : 2.2. Data fromthis 1997 study gives a ratio of 1 : 1.6, showing a possible 57% increase inbank erosion. Unfortunately, it is not known if the sites of "bank failures"measured by Prunuske Chatham were actual slumps or just eroding banks.There is no reported threshold for their identification of these features. Thusit is difficult to definitively establish that bank erosion has increased by 57%over the last 11 years or if the process of assessing is different.
(~ t)B k F 'Ih f StT bl 9 La e . engt 0 ream an at ures eeData Source Stafford to Grant Stafford to Sutro Sutro to Grant
Prunuske Chatham 9385 4495 48901986.
total lenl!th of fafluresCo11ins 1997. total 16488 8677 7811
length of eroding banks(> 0.5' bank retreat)
47
In 1977 the nearby 69 sq mi watershed of Walker Creek was assessed byWilliam Haible for changes in its longitudinal profl1e. Haible (1979) reported5' of incision in the uplands during 60 years, which equals a rate of 0.08' peryear, and aggradation in the lowlands of 4' at a rate of 0.07' per year (Haible,1980). This is twice the conservatively estimated rate for Novato Creek.Haible concluded that the whole longitudinal profl1e was adjusting to becomeless steep and that these adjustments of depth, velocity, and roughness werecaused by changing watershed conditions from cattle grazing. He also foundthat all the tributaries showed the. same sequence of aggradation anddegradation. Similar observations have been made in Novato Creekwatershed.
Changes in Drainage DensityThe drainage density (length of channel per unit area of drainage basin) ofthe watershed has increased since pre-European settlement due to earlyagricultural ditching, impervious surfaces, roads and road drains (includingdirt roads and ditches in the agricultural zoned areas), foot and cattle trails,gullies, headward extension of 1st-order channels, and incision of previouslyunchannelized alluvial fans. The extent to which drainage density hasincreased is unknown, but it has dramatically increased over the last 160years. This could also account for the downstream channel adjustments inchannel geometry.
The early etching of Rancho Novato, Appendix B4, shows that major channelssuch as Warner Creek were not connected to the main Novato Creek. It ispossible that Warner Creek and its tributaries spread out in a fan at the baseof the steep hillsides, causing the water to go subsurface and contribute to theoverall water table of the valley bottom. Warner Creek, which meets below S.Novato Blvd Bridge accounts for about 12% of the total drainage area. Clearly,the tidal channel below Warner confluence has had to adjust to flows andgravel-sized sediment that the Warner drainage ditch carried when it wasconstructed in the 1800's. .
Along the Sutro to Bowman reach of Novato Creek, several small streams thatflow from the southern grassy hillslopes were observed to have smallchannelized fans at the base of the hills. It is probable that many of thesesmall channels never reached Novato Creek prior to the 1830's because thechannels had insufficient capacity to carry the sediment supplied by debrisflow processes across the flat gradient of the valley bottom. Alluvial fanswere aggrading the base of the steep slopes and surficial flows infiltrated togroundwater supply before they reached Novato Creek. The tributariesdraining the slopes of Burdell Mountain may have been similarlydisconnected. As a result of increased runoff from grazed hillsides channels
48
eventually incised into the fans and directly supplied water and sediment tomainstern Novato Creek. These tributaries now convey water by subsurfacestorm drains through the urbanized areas of Novato. The process alluvial fanincision is documented from the field reconnaissance in Vineyard Creek. Firstorder channels have also been obsetved to be actively eroding headward inBowman, Vineyard Creeks and Arroyo Avichi. The obsetved processes inthese sub watersheds can likely be extrapolated to other unobservedheadward channels throughout the watershed.
The changes brought about by cattle grazing caused more water to betransported from the headwater hillslopes, which then had sufficient streampower to erode a channel into the fan and connect the supply of sediment andwater to the main Novato Creek. The generation of more water from the hillswas caused by the impacts of grazing, i.e., change in perennial bunch grassesto annual grasses, increased soU compaction, reduced infl1tration, and reducedinterception due to minimal thatch cover in early winter.
As Novato Creek incised, the tributaries that had been graded to a certainbase level also began to have upstream migrating headcuts. Some steps ornick points can be obsetved near the confluences of many of the channels.
If Novato Creek is still adjusting to relatively permanent alterations indrainage density by continuing to incise its bed upstream of the NFCP, thenexcessive bank erosion will continue, due to the greater shear stressesexerted by larger contained flows. As more trees collapse into the channel,the reduction in bank cohesion by loss of root strength will accelerate bankretreat (see Photo 267-268). For this reason it will also become increasinglydifficult to establish riparian vegetation within the entrenched banks untilsufficient widening occurs to create a floodplain within the high terracebanks.
Roads and Urban RunoffLike any urbanized development the increased impervious in imperviousareas has increased the drainage density of Novato Creek and effected thehydrograph in ways already discussed. It is worth noting that along theopen space and undeveloped areas very few gullies associated with roadrunoff were obsetved. Most of the paved areas have runoff that enters thestorm drain system and enters Novato Creek through a culvert, the location ofwhich were noted in the Field Notes.
Hillslopes and Landslides along Mainstem Novato CreekOn the hillsides adjacent to mainstem Novato Creek, there are few landslidesthat flow directly into the channel. Most of the channel is separate from the
49
slopes because it is entrenched within its broad alluvial terrace. Only theright bank occasionally intercepts the hillside canyon walls. The reacheswhere the landslides occur are Las Dias, Sutro & Bowman reaches, as shown inthe Pie Charts in Figure 11, where the percent of total length of bank effectedby landslides within each reach is 3%, 2% and 12%, respectively. The totalpercentage for the Diablo to Stafford reach is only 2.7%. Most of these slideswere more active in the past and appear to be stabilizing. Thus landslidesadjacent to Novato Creek, supply minimal sediment compared to local bankerosion. The types of slides ranged from earthflows (revetted by gabbions,Photo 160), debris flows (Photo 293), debris slides (Photo 193), to inner gorgedry ravelling within older landslide scars (Photo 287).
Gully erosion was minimal, but most prevalent in the Bowman and Sutroreaches where cattle pastures are situated along the left bank (Photos 264and 282). The lateral extent of these gullies is small. Gullies associated withroad erosion were not observed.
Conclusions for Mainstem Noyato CreekThe total conservatively estimated volume of sediment from bank erosion inNovato Creek is approximately 30171 cu yds. This total amount is only 67%of the volume of sediment that was dredged from the NFCP in 1996, which.was· about 45,000 cubic yards. Even if this conservative estimate wasdoubled, similar volumes of sediment have been dredged in years past. Thisindicates that significant sediment sources exist elsewhere in the watershedand that tributary channels must be additionally transporting high amountsof sediment to the NFCP. The volume of sediment from the banks can bevisualized by spreading it over the bed along the length of the Diablo-Staffordstudy reach. If the bed averages 25' wide, the sediment from the bed wouldraise the bed 0.9' thick. However, the bed presently stores more than thisamount of sediment, based upon observations of gravel bar height. Theseobservations indicate that a high proportion of the sediment load is providedfrom sources other than local banks and terrace erosion of Novato Creekproper.
To a small extent the additional sediment sources that might account for thelarge amount of sediment stored in the creek bed of the Diablo-Stafford studyreach include adjacent hillsides. However, the sediment supply from thehillsides is exceeded by the supply from banks and terraces.
Bankfull discharges appear capable of transporting and distributing the loaddownstream to the tidal reaches.. No particular site appeared completelyoverwhelmed by sediment although local aggradation was occasionally noted.The amount of storage, as bars in the channel bed, was greatest in the reaches
50
that have widened enough to become Rosgen B-type channels and it is inthese areas that terrace bank erosion is shutting down and habitat complexityis greatest. The rest of the entrenched G and F-type channel, which comprises
. most of Novato Creek, effectively transports the sediment eroded from localbanks and conveyed by tributaries to the NFCP.
The'reduction in tidal channel gradient caused by diking of the marshes,realignment, channelization, dredging, and backwater from the NWPRRBridge, has caused the NFCP to become a sediment trap that cannot, underpresent conditions, maintain the desired design capacity without continueddredging. The bulk of the deposited sediment in the NFCP is from uplandsources as demonstrated by the gravel-sized sediment deposited beyond therailroad bridge and the organic matter that ranges in size from large woodydebris to leaf litter.
The adjustments in channel geometry and stream gradient are associatedwith land practices during the last two centuries. Two dominant periods ofchannel incision appear to be associated with 1) the early to mid 1800's whencattle grazing and agriculturaI development of the valley began, and 2) themid 1900's when Stafford Dam was constructed. Sediment production fromcombined bank erosion and bed incision appears greatest in the reachesclosest to the dam. The channel gradient from NWPRR.Bridge to Stafford Damis effectively flattening by incision in the uplands and deposition in thelowlands as it adjusts to sediment load contributed by the entire watershed
: that is much greater now than prior to the early 1800's. The total amount ofwater supplied to the channel has increased since this time due to greaterdrainage density caused by headward extension and connection of tributarychannels, urban storm drains, ditches, impervious surfaces, and impacts ofcattle grazing. Steam flow and its distribution has been altered by waterdiversion and retention in Stafford Reservoir. Sediment supply from bankerosion of just Novato Creek has compensated, in part, for the trapping ofbedload upstream of the dam. The fact that the total volume of sedimentsupplied from the banks is only 67% of the amount of one cycle of dredging inthe NFCP indicates that there is substantial supply and transport from thefive main tributaries of Leveroni, Bowman, Warner, Vineyard and ArroyoAvichi.
51
BOWMAN CREEKGeneral BackgroundBowman Creek is within a 3.1 sq mi watershed in the northern portion of theNovato Creek watershed, Figure 2. Vegetation in Bowman watershed is amixture of grasslands on the south facing slopes ranging to mixed oak-baywoodland on north facing slopes. The main Bowman Creek flows southwardfrom an elevation of 1458' to about 140' where it meets the Novato Creek atDistance Station 220-51'. Data collection of the mainstem Bowman Creekextended from Station 0-00 at the confluence to 29-74' upstream. Furtherdata collection in the channel was not possible when trespass was prohibitedonto private property. Unlike the other main tributaries to Novato Creek,landslides were mapped and a hillside reconnaissance was performed toassess headwater channels and to verify landslide interpretations. Thehillside reconnaissance has station numbers that correspond to stations shownin Photo Album II and the topographic map, in Figure 18.
Hicks Valley Road crosses Bowman Creek at Station 2-87' to 3-25' upstreamof Bowman's confluence with Novato Creek. The possible extent of backwaterinfluences from Novato Creek and the hicks Valley Road box culvert mayextend to Station 6-25'. The study reach flows mostly through alluvium ofterrace deposits, but in two reaches we called 2A-type (Field Notes, AppendixD), bedrock and canyon slopes are intersected along the right bank. Thesebedrock reaches may have slightly steeper gradients than the alluvialreaches.
Historical and present day land use in Bowman watershed has been primarilycattle grazing and dairy ranching. A number of unsurfaced ranch roadsaccess the ridges and valley lands. There is also a gravel quarry in themiddle of the watershed on a small, isolated hill. It is presently inactive andrunoff drains into a sediment catchment basin.
Channel Reaches and Rosgen ClassificationDUring the reconnaissance Bowman Creek was divided into geomorphicreaches, as discussed herein. There is no map accurate enough to display thechannel Distance Stations for Bowman Creek. Reach 1 extends from theconfluence to 8-37', see Photos # 302 and 305 for example. The channelflows continuously through alluvium. Many of the banks are composed ofgravels. It's Rosgen Stream Classification is G4-G5. Bank erosion and bay treeroot exposure is pervasive. Many of the trees are still standing upright alongthe terrace banks even though they have been severely undermined. Thesetrees form a continuous riparian canopy and few other vegetation types arepresent between the bare terrace banks. The reach is dOminated by
52
I
i
;. '.I •
" ) (I; ,I
..', >
I·'. \,I
abundant fme gravel and sand. There are no significant pools, yet trout fryare observed. This reach is influenced by backwaters that fonn from highflows in Novato Creek and from debris that catches at the Novato Blvd Bridge.Such backwaters have contributed to the deposition of gravel bars that are asmuch 2.3' high.
Reaches 2a, from 8-37 to 9-78 (Photo # 315, for example) and 12-22 to 1335, have steeper slopes, tend to be narrower, and intersect bedrock from theRB hillside. Rosgen classification is G4. This reach may also be above possiblebackwater influences from Novato Blvd Bridge. Larger cobble-sized clasts arecontributed from the hillside. Plant diversity along the channel is slightlyhigher because of the hillside soils providing a different substrate than thealluvium. Poison oak, snowberry and ferns are occasionally present. Therelative proportion of gravels to sand is slightly greater than in Reach 1.Gravels are also larger.
Reaches 2b, Station 9-78' to 12-22' and 13-35' to 18-35' (Photo 318) haveterrace and bankfull banks that do not intersect hillsides. Bay treespredominate the terraces but there are more grasses and herbs beneath thetree canopy. Stream gradient is gentler than 2a reaches. This is a Rosgen G4type channel but bankfull width is wider and terraces are higher than 2areaches.
Reach 3 extends from 18-35' to 25-22'. It is an extremely wide reach in opengrasslands with no trees on the banks. The trees may have eroded away longago. Segments range from a G4 to something between a C4 and B4 RosgenClass, see Photos # 22 and 26. The terrace banks are mostly fines but havelenses of gravels. Bank erosion has been significantly higher in this reachthan any of the others due to lack of root strength in the banks. Several setsof terrace banks exist in this reach with the highest being over 14'. Apredominant inner terrace between a meander bend is about 8' b~low thehighest terrace and a smaller less developed terrace is about 10' below thehigh terrace. The latter may have been the bed level of the fonner channel.The current floodplain, which was likely a former bed level, is about 1.8'above the present bed level. This reach may have changed from a Rosgen Ftype channel to a C-type channel.
Reach 4 analysis is incomplete because we could not continue on privateproperty. Most likely this section is similar to the 2b reaches, see Photo #332 for example.
Bank Condition
54
Although the lateral extent of eroding banks and revetment was notmeasured for any channels other than Novato Creek, notes were taken aboutthe amount of bank retreat at discrete points during the Bowman Creekreconnaissanc~. The Field Notes and Bowman Creek Data are located inAt!Pendix.D.
Maximum bank retreat measured was 14' at Station 22-50. The average ofall point measurements is about 7.1 '. Since these measurements tended to betaken at the more severely eroded sites, but also noting that bank erosionappeared almost continuous throughout the study reach, a more conservativeestimate of a foot or two less might be plausible for the average amount. Onthe other hand, analysis of width between the exposed roots on the terracebanks sugges~ otherwise.
For example, at Station 8-60 the width of the channel between exposed rootsof bay trees growing on the terrace demonstrated that the historical channelwidth used to be narrower: about 12' wide when the valley flat (present dayterrace) was the functional floodplain, as compared to the presentlyentrenched 16.5' bankfull width at this station. Near this site some channelwidths, between roots along the terrace banks, range from as little as 6'-9'.Three other sites where bank erosion and bankfull width were measuredshoweq that the historical channel width was 10', 12' and 14'. If all thediscrete point measurements of present day bankfull width were averaged,21' would represent bankfull width. If the average bank erosion value of 7.1 'is subtracted from the 21' bankfull width, then the historical average bankfullwidth would have been about 14', which is on the high end of the fourhistorical width measurements. The estimated historical widths indicate thatthe estimate of 7.1' average bank erosion for Bowman Creek study reach maybe reasonable. .
Bank condition was also observed on Two Lewis Creek tributary, which isconfluent to BoWman Creek, see Figure 18. In some areas it has eroding,unstable banks that exceeded 18' in,height and it has evidence of continuousbank retreat as demonstrated by exposed tree roots, see Photos 351 through356 The rate of supply of fine sediment per linear foot of these ,banks isexpected to be chronic and exceptionally high.
~Regional curves for the Bay Area (Leopold, 1994) predict that bankfull widthshould equal to about 23', mean depth should equal 2', and cross sectionalarea 46 ft2. Measurements collected in the field for this study give averagesof 21', 1.9', and 40.5 ft2, respectively. The historical channel, as of about 165years ago, may have had a narrower and deeper channel geometry, and it
55
would have been less entrenched. This would be due to the lower amount ofrunoff coming from the hillsides that had not yet been grazed or converted toEuropean grasses. Based upon the width measurements between roots on thehigh terrace and the amount of measured bank erosion, if the historicalaverage bankfull width was somewhere between 7.1' to 14' , and grosslyassuming that bankfull cross sectional area would have been 90% of thepresent amount because of reduced drainage density, then mean depth couldhave been between 5' and 2.5', respectively. Perhaps depending uponwhether it was in a bedrock or an alluvial reach.
Channel geometry was also noted on the third order tributary Two LewisCreek. At Station 19 the configuration of roots in Photos 359 and 361silhouetted the former shape of the channel before it was entrenched. Thehistorical cross section was about 6' wide by about a maximum of 1.5' deep.The cross sectional area may have been about 7 fi2. The present channel ismuch wider, shallower and entrenched. Slightly downstream at Station 14,the bankfull width is 6' and may have a bankfull depth of about 1.8'.Determination of bankfull. was imprecise since the channel was activelyincising. The best guess of mean bankfull depth is about 1.8'. This suggeststhat at this site the historic bankfull cross sectional area was 83% of today'samount, substantiating that the channel has had to adjust its bankfull crosssectional area to accommodate more runoff.
From the analysis of the historical stereo photos of Bowman Canyon, it isapparent that the process of headward erosion of fIrst order channels, bankerosion of all orders of channel, and incision of fans at the base of steepcanyons was well underway by the 1950's. Field analysis verified that theseprocesses are still ongoing and perhaps most active within headward reaches.For example, Photos 336 and 337 show a headcut migrating up into a tinyephemeral channel. The cross sectional area for the gully is about 20 timesgreater. Photos 344, 345 and 346 show the same phenomenon on anothertributary where the difference in cross section is similar. Many of theheadwater reaches in Bowman Canyon are anticipated to be in a similarcondition.
Bed Condition Relative to Pools, Wood and Sediment StorageFigure 19 shows the results of the pool and woody debris analysis for the2974' long study reach in Bowman Creek. The upper pie chart shows the totalnumber of pools greater than l' deep within the study reach was 8. One poolwas formed by rip rap, three were from bends, two were from bay treetrunks and the other two were from woody debris. The total number of poolsis less than that which would be normally expected for every 5-7 bankfullwidths. For example, assuming that the average bankfull width is 21', pool
56
CharacteristicsWoody DebrisReaches
andAll Study
Poolfor
CreekBowman
CAUSES OF POOLS GREATERTHAN " DEEP
12% l\IIarHnade structures(bridges, cement, rip raptransported from bankstabilization projects)
IIIUJ Wood (tree trunks, roots,wocxJy debris, debris jams)
IIIUJ Other (bends, bedrock,lBs, boUders)
II Undetermined
Bowman CreekTotal # of pools = 8, average pool
spacing = 368', study reach distance = 2974'.
TYPES OF TREES COUNTED AS LARGE WOODY DEBRISBELOW BANKFULL HEIGHT
o
Bowman CreekTotal # of LWD =13
I'm~ Bay Tree
Oak Tree
{t~l t i·C~ :}( E~ ~i ~:'~ ':rT1 ti (; ( C:' [1 {~ 8~
t;:~~(11.::~:rt.';t\~:r(v· j
·n·I~3 t';1 t
DEBRIS JAM CHARACTERISTICS 0%
III Across channel bed
[ill] Partly blown-out
O· ··, .. ·· .. '·1-"'··,' I; .~., I :; !~I t! ,.
FIGURE 19Bowman Creek
Total number of debris jams = 6
should be spaced within 115'-175', but Bowman Creek pool spacing was only368' (equal to 17.5 bankfull widths), indicating that even though the channelhas perennial flow, sediment load overwhelms the capacity of the channel tomaintain pools deeper than 1'.
The middle pie chart shows that all the large woody debris in the channel wasfrom bay trees. The lower pie chart shows that of the total of 6 debris jamsnoted, none of them fully blocked the channel.
Sediment storage within the active bed was also quantified from stations 347' to 21-33'. For this 1786' long reach, total volume of sediment in storage,above the mean bed level, was 482 cu yds. If this amount was spread outover the length of the channel, on a bed that averaged about 16' wide, thenthe amount of fill above the mean bed level would equal 0.46'. If the volumeis divided into the appropriate amounts for Reach 1 (backwater influencedarea, 483') and Reach 2 (upstream of backwater, 1303'), then the height of fillwould equal 0.33' and 0.81', respectively. This corroborates that Reach 1 ismore of a depositional reach. than Reach 2.
Within the Two Lewis Creek, sediment storage within the bed was low.Sediment on the bed was usually a shallow veneer, usually less than 10% thelargest cobble4sized particles that were left behind as a lag deposit, seePhotos 352 and 364 for example. This is because the discharge and gradientare sufficient to transport most of the supplied sediment to the lowergradient reaches.
In the observed steep headwater channels sediment storage on the bedranged from minimal where debris flows had scoured to bedrock (Photo 339),'to minor where the bed was composed of coarse gravel and cobble lags ofcolluvium or debris flow deposits (photo 335). Where slopes were less steepor where there was no source of coarse-sized colluvium the bed wascomposed of fme soil-sized particles derived from either erosion of gullywalls (Photo 336) or surface erosion of grassland soils by overland flow andraindrop impact (Photo 346).
Reading Trees and Rates of IncisionThroughout the length of the study reach on main Bowman Creek, there isevidence that there were two periods of relative channel stability, see Photo #313 for example. These periods are represented by roots at heights thataverage for the whole study reach about 5' and 8.7' below the terrace of thevalley flat, which has an average height of 10.7' above the bed. Theseelevations may represent fonner stable bed levels. In the reaches wherehistorical channel width was 6'-9' wide, bankfull depth must have been at
58
least 5'. If the channel, like Novato Creek, has cut down 5' in the last 165years since the onset of grazing, and 2' since the construction of Stafford Dam,(which lowered the base level of Novato Creek thereby producing a migratingheadcut through Bowman Creek), then the earlier downcutting rate wouldhave equaled 0.031' per year and the 2' of recent incision would have a rateof 0.043' per year. The long term average would be 0.34' per year. Theserates correspond to the rates reported for Novato Creek.
On the third order Two Lewis Creek tributary at Station 19, roots of a baytree were exposed 4.5' above the channel bed, see Photos 359 and 361. Thebay tree is estimated to be no older than 100 years. This would give adowncutting rate of 0.045' per year. Downstream at Station 15, Photo 353shows a person standing on roots that define a former bed. The current bed is2' lower, corresponding well with the observed recent 2' incision level inBowman Creek.
At Station 20 , Photos 362 and 364, a second order tributary channel to TwoLewis Creek has a bed that is showing incision within a few feet of theconfluence. A few feet back it's bed is 5' higher than the bed of Two LewisCreek. This corresponds to the stable root level noted in mainstem BowmanCreek and the level of the exposed, roots at Station 19. The recently exposed.tree roots indicate that an active headcut is beginning to incise the secondorder tributary.
Hills}opes and..Lan9s.1ides in Bowman Waters~Figure 18 shows the distribution of recently active landslides in BowmanCanyon, as mapped from the 1995 stereo photos, that have moved within thelast 25 years. The area outlined in pink shows the boundary of the areainspected during field reconnaissance. Without substantial fieldreconnaissance it is not possible to determine the linkage of all the slides tothe channel network, especially for those within the tree covered slopes. Thelandslide mapping does demonstrate, however, that numerous slides exist atthe heads of first order drainages and at isolated locations on the hillslope.The active slides were shallow features that ranged in type from slumps tosoil slips.
Slides at the heads of drainages within the zero order basins are obViouslymore problematic at supplying sediment to the stream system than the slideson the open hillsides. Not only because they have direct input to the channel,but because when the debris slide occurs, it tends to scour all the sediment inits downstream path until it can either be deposited at a lower gradient oruntil it is sufficiently diluted by additional tributary flow that stream flowcan continue to transport it as bedload. The total amount of sediment that
59
becomes bulked within the debris flow can ultimately be orders of magnitudelarger than the initial shallow failure at the head of the drainage. Within theobserved reconnaissance reaches, sediment input to channels from landslideswas mostly associated with saturated hillslope conditions at the heads of firstorder channels rather than from removal of lateral support by stream cuttingalong the channel length.
The active failures in Bowman Canyon do not typically have their entire scarfully evacuated of sediment, see photos 340-343, and 347-348. Instead, theslump areas in particular may be fairly chronic suppliers of fme sedimentsevery few years since their episodic movement may occur with storms thathave a recurrence interval of 5-15 years, and the time required forstabilization and revegetation may be 10 to 25 years.
Shallow landsliding and slumping appears as though it might have been moreactive in the 50's than in 1995 when the stereo photos were taken. An initialhypothesis is that the frequency of shallow landsli(Jing has increased sincethe mid 1800's. Such an increase may be largely due to associated grazingand conversion of perennial, native bunch grasses to the annual Europeangrasses. Such conversion would decrease soil cohesion that helps resistlandsliding on steep slopes because: 1) the roots of the perennial grasseswould remain viable year round, whereas roots of the annuals decay duringwinter; 2) the bunch grasses have much deeper rooting depths than theannuals, often 6' for perennials as compared to 3' for annuals; and 3) soilsaturation that causes slides would occur with less rainfall, since soil coverageof remaining thatch of the grazed, dead annual grasses would be much lessthan the thatch associated with ungrazed, viable bunch grasses.
As drainage density has increased from more runoff in the grasslands andchannel heads have migrated upslope, unchannelized fans have also becomeincised, channels have adjusted their geometry to larger bankfull djschargesby entrenching, and gullies have dissected the hillsides. Within the zeroorder basins, it may be likely that the modern landscape has more shallowlandslides than there were 165 years ago and scouring from the resultingmobilized debris flows has moved channel heads upslope to the base of thedebris slide scars. The formation of gullies may also be more likely in theconverted grasslands. For example, surface erosion is more likely if there ismore runoff and if the soil cohesion is reduced. Both of these requirementshave been achieved. Photo #338 shows an example of a gully that ispresently stabilizing. In concept, if grazing practices in this watershed weremost intensive during the earlier part of this century, then improved landmanagement strategies and grazing practices could account for the morestabilized appearance of the landscape in 1995 (and 1997) than in 1950.
60
As grass conversion and grazing proceeded to increase runoff and channelentrenchment, it is possible that downstream transport of mobilized landslidedebris has concomitantly become more proficient and residence time forstored debris flow sediment may have similarly decreased. For example, if a,debris flow is carried within a shallow or wide channel, the slurry can spreadout over the banks as berms (where its residence time as stored sedimentwill likely be long) or as bars within the channel bed where the gradientflattens. If the channel becomes deeply entrenched then sediment will bekept within the banks of the channel (thus no long residence times), shearstress to banks will be increased (thus more sediment will be entrained andtransported), confinement within entrenched channel banks will carry moreentrained sediment farther, and larger bankfull discharges will more rapidlyrework and transport sediment stored on the bed. .
Landslides are an important landscape forming mechanism in the watershed.But it appears that recent contributions of sediment from individuallandslldesources in Bowman Canyon is less significant than bank/terrace erosionsources throughout the stream network.. Especially since the latter sourcessupply sediment more chronically than the hillsides. The historic landscape'of 165 years ago may have been the opposite case such that landslides werethe predominant sedIment source before channels became entrenched. Themodern landscape has effectively shifted the importance of sediment supplyfrom mass wasting to fluvial erosion. The entrenched stream network is the
, product.
Roads and TrailsThe unimproved ranch roads that were inspected within Bowman Canyonhillsides did not typically have inboard ditches, high cut banks, or significantfills, see Photo 341. Few gullies were observed to be associated with roadrunoff. Although the dirt roads contribute to the production of fme grainedsediment that is transported in suspension, the overall impact of roads as asediment source in Bowman Canyon does not appear significant compared tobank erosion or landsliding. The greatest impact is likely the effect of roadsupon increasing and concentrating runoff to the channels, thereby increasingthe overall drainage density and the rate at which water is delivered to thestream. Cattle trails are observed to have a similar effect.
~The number of cattle trails on both banks of the main stem Bowman Creekstudy reach was 19. Each of these trails was associated with inputs of flnesediment that contribute to the wash and suspended load from both banks.Runoff from the pastures located on the terraces was commonly funneled
61
down these paths so sediment contribution was not just from the banks alone.If cattle trail spacing is determined the same as per pool spacing, then thespacing for the 2940' long reach is 154'. Since most trails are associated witha nearby trail on the opposite bank, it may be better to consider trailcrossings as spaced about every 300'. Since no data has been collected on thedensity of cattle trail crossings in the past, it is impossible to compare thisnumber to any other stream. Yet, based upon the impacts of the trails, thisnumber seems unnecessarily high and could be reduced by fencing, therebyreducing some of the immediate input of fme sediment.
~imentCharacteristicsBased upon observations of stream turbidity during storms, suspendedsediment load from Bowman Creek appears quite high as compared to thatupstream in Novato Creek at the confluence. Flow from Bowman Creek has adistinct orange coloration during storm flow, perhaps from the volcanic rocksin the watershed. The amount of fine material in the bed of Bowman Creekappears much greater than that in Novato Creek, where most of the bedloadbelow the dam is supplied by Leveroni Creek. Of the tributary channelsBowman Creek is suspected to be supplying the largest proportion of bothbedload and suspended load to Novato Creek for average bankfull flowconditions. During extreme storms it is not known if the concentration ofsuspended load that comes over the spillway at Stafford Dam is greater.
The fmes that emanate from this watershed are associated mostly withterraces and banks which are composed of mostly fme sediment particles,even though gravels are also a component. To a lesser extent each of thefollowing other parameters also contribute fine sediment: hillslope soils,gullies, landslides, roads, concentrated dairy activities, cattle trails, andabandoned quarry. The relative importance of the combined totalcontribution of sediment from all these other sources compared to that frombank erosion alone can not be estimated within the scope of this study, butshould be considered in the construction of any sediment budget that mightbe done for the watershed.
Conclusions for Bowman CreekThe quantitative and qualitative analysis indicate that Bowman Creek has ahigh supply of sediment generated from bank erosion. Most of this sedimentis sand and finer sizes. Cattle grazing activities directly and indirectly havecontributed to the entrenchment and increased sediment production withinthis watershed. Bowman Creek has the competence to transport its suppliedbedload to the point of backwater influences from Novato Blvd. Bridge andNovato Creek confluence. Within the backwater influence zone someproportion of the bedload will temporarily aggrade the bed but be reworked
62
at lower flows. The suspended load moves entirely through the system toNovato Creek. Sand may comprise a high proportion of the suspended load.The wash load may become some of the reworked silt and fmer-sizedsediments associated with the tides.
LEVERONI CREEKLeveroni Creek, as named in this report, is confluent to Novato Creekdownstream of the Stafford Dam Spillway and about 3000' upstream ofBowman Creek, see Figure 2. Its drainage area is roughly estimated at 1.5 sqmi. Principle land use in the drainage is dairy ranching. Reconnaissance wasvery limited within this watershed since access was denied by the privateland owner. We observed a continuous 1,070' of channel upstream of itsconfluence with Novato Creek. The hillslope relief extends to 1219'.Vegetation patterns are similar to Bowman Canyon with grasslandspredominating.
For the short distance observed, evidence of vel)' recent bed incisionappeared to be on the order of 2'. Evidence of earlier periods of erosion and
. stability was consistent with that observed in Bowman Creek. Based upon acrude approximation of tree ages, we estimated that 2' of bed incision hasoccurred over the last 45 years, yielding an erosion rate of 0.04' per year.
Abundant sand and gravel-sized sediment choked the channel bed with barsas high as 2.2'. Within the observed reach, terrace and bankfull bank erosionprOVided a high localized supply of sediment. Terrace banks averaged about11.5' high. In some areas the channel bank retreat was a full bankfull widthof about 14.5'. Due to the excessive bank erosion, we observed 7 debris jams(3 of which fully crossed the channel) within the study reach. The spacing ofdebris jams, 1 per 152', was much closer together in Leveroni Creek than anyother reach observed in Novato Creek. The spacing distance was half thatobserved for Bowman Creek. Bay trees, oaks and willows contribut~d to thesupply of large woody debris.
Based upon cursory observations of the hillsides, surface and gully erosionfrom the heavily grazed grasslands is an important source of sediment that ismore significant in this watershed than any other observed in Novato Creekdownstream of Stafford Dam. During a1998 winter rainfall, rill networks andoverland flow was observed on some of the over-grazed hillsides where littlethatch 'cover existed. Like Bowman Creek, cattle trail crossings were alsoproviding much fine sediment to the channel. The impact and extent of ranchroads was not observed.
63
For the small size of Leveroni Creek watershed, sediment supply appearsdisproportionately higher than the other major tributaries.
VINEYARD CREEKac;kgroundVineyard Creek has a drainage area of 1.69 square miles. It flows eastwardfrom a relief of 1575', see Figure 2. The headwaters are mostly oak/baywoodlands and the lowlands are developed for suburban residential use. Theland use and fire history are not known for this area and should beresearched. Reconnaissance of the upland channel heads and landslidemapping was not within the project scope.
Reconnaissance was performed on about 10600' of channel length, includingthe lower portions of several tributaries. Field Notes, located in Appendix F.record the observations for taped Distance Stations over a 10110' channellength. The lowermost section of Vineyard Creek, below Wilson Ave, is an oldditch (see Photos 419) that meets the Warner Creek ditch near the bend inWilmac Ave, see Watershed Maps 9, 10 and 11. Before the ditch to WarnerCreek was constructed it is not known where or if Vineyard Creek everconnected to Novato Creek. It may have been entirely disconnected by anunchannelized alluvial fan at the base of the hills. This needs furtherinvestigation. If this is true, the drainage density to Novato Creek would havesignificantly increased causing a subsequent alteration in channel geometry toadjust for more water and sediment. Upstream of Wilson Ave VineyardCreek has natural meandering, tree-lined terrace banks that are activelyeroding, similar to portions of lower Bowman Creek, see photos 438, 463 and495 for example. Within the study reach, bedrock is frequently interceptedand several steps in channel gradient were found to range from 2' to 4'. AtStation 44-67' there is a spillway that causes a grade change of 8'.
Rosgen Classification typically varies in the valley bottom reaches from G4, F4and B4. Since suburban development has occurred along the terrace banks,bank revetments of sackcrete, riprap and concrete are found.
GeometrYFor the reach between Stations 0+00' and 51-10', the average width of a lowgeomorphic bank was 12.9'. According to Leopold's regional curves (1994)the cross sectional area for bankfull should equal 31 sq ft with widthaveraging 17' and mean depth equal to 1.8'. The geomorphic bank that wemeasured in the field is too low, according to the regional curves, to be aassociated with mean annual flow or bankfull. Our low bank generallyprovides a cross sectional area that is half of Leopold's predicted value. Inone section of channel we were able to determine that the "older pristine
64
condition" bankfull was probably about' 14' while the new bankfull hadadjusted to 21'. The range of our low bank widths was from 8' to 22.5'. Onepossible explanation is that our low geomorphic banks represent a buried
, bankfull of a previous bed level that has subsequently become incised.
Bank retreat measurements average 3.4'. Figure 20 shows a representativecross section that was taken at Station 29-90 that typifies the general look ofa G4 Vineyard Creek reach.
~ ConQjtion Relatiye to f.QQ)s. Wood and..se.d1ment StorageOver the full reconnaissance including the channel downstream of Station0+00, we observed 34 pools, seven of which had trout in them. The largestfish was 10". Figure 21 upper pie chart shows the causes of pools greaterthan l' deep in' Vineyard Creek, from Station 0+00' to 50-00'. About 38% ofthe pools were formed by natural conditions such as bends, 'bars, bouldersand bedrock. The data is located in Appendix. F. Another 31% were formedby wood such as roots, tree trunks and debris, and 31% were associated withman-made structures. The middle pie chart of Figure 21 shows that of only 4pieces of LWD, 67% enteriiig Vineyard Creek is from willows, while 33% isfrom bays. The lower pie chart shows that two debris jams extend all theway across the channel.
ChanneUncisionIn general, in the lower natural portions of Vineyard Creek, the channel
, appears to have gone through an initial phase of bed incision and bankerosion. It is now aggrading its bed and continuing to erode its banks. Thissuggests that either sediment supply has increased from upstream bankerosion thereby overwhelming the channel capacity and causing a decrease inchannel gradient or the local bank erosion has significantly widened thechannel to cause a flattening of the slope and hence aggradation. Acombination of both scenarios is hypothesized since extensive erosion ofchannel bed and banks was observed ubiqUitously.
Very recent bed incision does not appear to be as abundant or as active asother Novato Creek tributaries, possibly because of the scenario ofaggradation that has followed initial incision. Between Stations 0+00' and SI10', recent bed incision averages about 1.36' but the depth to maximumincision is obscured by recent deposition in many reaches. Overall patterns oferosion and stability for the last 165 years was not determined for VineyardCreek. The construction of Warner' ditch in the 1800's and its connection toVineyard Creek may have influenced rates and timing of bed incision withinVineyard Creek.
6S
Vineyard Creek, Cross Section 29-90Terrace cross sectional area = 79 sq ft
35302510 15 20Distance (ft)
5o
5.000
15.00
10.00
o.000........;-;-;....;.;-,i-t-+f+t...;.+;....;.;-,io-i-t-.......~~..............................
-5
FIGURE 20
Vineyard Creek Pool and Woody Debrisfor Study Reach between 0+00' AND
Characteristics50-00'
CAUSES OF POOLS GREATERTHAN l' DEEP
121 Man-made structures(bridges, concrete, ripraptransported from bankstabiliztlon projects
IIID Wood (tree trunks, roots,woody debris, debris jams)
III Other (bends, bedrock,bars, boulders)
• Undetermined
Vineyard CreekTotal # of pools =32, average pool
spacing =160') study reach distance = 5110'.
TYPES OF TREES COUNTED AS LARGE WOODY DEBRISBELOW BANKFULL HEIGHT
Vineyard CreekTotal # of LWD =4
o
m Bay Tree
!ill Oak Tree
DEBRIS JAM CHARACTERISTICS 0%
Vineyard CreekOf the total 2 debris jams
III Across channel bed
liliI Partly blown-out
FIGURE 21
Several small tributaries were inspected along the western headwaters ofVineyard Creek. These sites are shown as either LB or RB designations in theVineyard Creek Station Map in Appendix F, and are shown as Photos 560through 575. Pages 13 - 15 of the Field Notes for this section correspond tothe photos. The data show that the actively eroding headcuts through alluvialfans have an average incision of 3.8' t much greater than the average for thevalley bottom channels. Additionallyt the cross sectional area of the bankfullflow is much less than the cross sectional area of the total gully. The bankfullcross section often represents only 15% of the total volume of soil removed.demonstrating substantial sediment supply from these small channels.Examples include Station LB #3 where an additional 8.4 sq ft has beenremoved by a bankfull cross sectional area of 1.5 sq ft and Photo 544-45shows where 22 sq ft has been removed by a bankfull cross section of 4 sq ft.These small upland channels are exhibiting rates of very active bed incisionthat exceed rates along the higher order, valley bottom channels. The fieldevidence indicates that incision is related to upstream increases in flow ratherthan headcuts propagating upstream from a change in base level of the mainchannel, see Photo 573 and corresponding Field Notes.
Only one tributary of 8 observed in the headwaters of Vineyard Creek, RB #2,shows evidence of a stable channel. It has moss covered rocks and minor bedincision. The change in cross sectional area is only 0.58 sq ft. Why thischannel is stable and the others are actively eroding has not beeninvestigated. ..
Hillslopes and Landslides in Vineyard WatershedOnly a few small landslides were observed along Vineyard Creek, Photos 571and 574 for example. Contribution of sediment from landslides in thiswatershed is estimated to be relatively low compared to amounts providedby bank and bed erosion. Some of the steep tributaries are occasionallyinfluenced by debris flows as indicated by the presence of boulders, Photos575 and 579 for example.
Roads and Urban InfluencesPaved and undeveloped open-space trails undoubtedly increase the drainagedensity in the watershed and therefore contribute to increased runoff andpeak of the hydrograph. Their extent and impact was not directlyinvestigated.
for VineYard CreekVineyard Creek's main influence on Novato Creek may have been the addeddrainage density it provided when it was connected to the Warner Creek
68
ditch. It presently supplies and stores abundant quantities of sediment. Theamount that actually gets mobilized to Novato Creek is unknown.
WARNER CREEKWarner Creek has a drainage area of 5.18 sq mi, and includes Wilson andVineyard Creeks, see Figure 2. Based upon historical evidence such as theSubdivision Map shown in Appendix A4, Warner Creek is a man-made ditch.Its age is unknown but it may predate the 1850's when apple orchards werein full production in central Novato, see Rancho Novato Etching in~.There is no indication that a previous channel existed along the ditchaIlgnment, and whether Vineyard Creek ever connected to Novato Creek isquestionable. Excluding the upstream tributaries of Vineyard and WilsonCreeks, the principle land use along Warner Creek drainage is suburbanresidential development. The ditch is entrenched within terrace depositsalong its entire length.
The lower portions of Warner Creek from its confluence of Novato Creek tothe South Novato Blvd Bridge crossing became part of the Phase IV NCFCP in1990, and by 1995 the Project extended to McClay Bridge. During fall 1997sediment dredging was performed from the mouth of Warner Creek to DiabloAve Bridge. Because the whole channel is a constructed ditch, we did notassess the numbers of pools or make detailed notes relative to streamDistance Stations. Instead we performed a general reconnaissance andrecorded some observations which are noted in~ Field Notes for
.Warner Creek. Photographs of Warner Creek are shown in Photo Album II.Warner Creek meets Novato Creek at Station 20+00', as shown on WatershedMap 1. Watershed Maps 8 and 9 show its upstream continuation to VineyardCreek.
Our reconnaissan~e indicates that the ditch of Warner Creek, since the time ofits construction, has undergone perhaps at least 2' of average bed incision,and ranges up to as much as 3.5' at discrete locations. In several sectionsincision has extended into silty clay beds of Quaternary Alluvium, see Photos384, 388 and 404. Extensive sackcrete revetment has been placed along thebanks of the ditch, and in areas where both banks have been revetted, bedincision appears most pronounced. Presently, the process of channel incisionappears to predominate over bank erosion in Warner Creek. The decreasedroughness associated with sacreted banks likely imparts higher watervelocities and higher shear stresses on the channel bed. Interestingly, wehave observed evidence that the channel often cuts to the level of the footerditch that is excavated below the original channel bed. Concrete apronspoured over the remaining bed during the time of construction now standwell above the present bed level, see Photo 393. It is likely, however, that
69
most of the channel incision is associated with a combination of changes inchannel geometry that have been caused by increased amounts of upstreamrunoff and by poor hydraulic design of the original ditch. Photo 402 and 406show a series of headcuts in the channel bed that have 3.5' and 2.5' steps inthalweg gradient at tree roots. These roots indicate a former bed level of theditch. Its original dimensions are unknown.
Sediment storage in Warner Creek is only abundant in an alluvial fan atWilson Creek confluence, Photos 392. A fan at the Novato Creek confluence isalso evident, Photo 22-23. Elsewhere, Warner Creek has sufficient capacity totransport its sediment load through the system. Vineyard Creek has anample sediment sources, the relative amount that is transported to WarnerCreek versus stored within the bed of Vineyard is unknown. In some areasArmorlock is the largest sediment size mobilized, see Photo 371.
ARROYO A VICHIGeneral BackgroundArroyo Avichi has a drainage area of 1.78 square miles. It flows northwardfrom a relief of 1280', see Figure 2. The headwaters are mostly oak/baywoodlands and the lowlands have suburban residential development. Landuse and fire history are not known for this area and should be researched..Reconnaissance of the upland channels and landslide mapping was not withinthe project scope.
Reconnaissance was performed on about 10500' of channel length. The FieldNotes, located in Appendix C, record the observations for taped DistanceStations from the mouth of Arroyo Avichi at Novato Creek confluence tobeyond the Indian Valley Road Bridge. Photo Album III shows correspondingphotographs. Bedrock was frequently intercepted and several steps inchannel gradient were found to range from 1.7' to 2.8'. The lower portions ofArroyo AVichi, generally below Station 43-70' are intermittent with a fewisolated pools. There is a small dam at Station 60-67 that has a SA' change ingradient. Rosgen Classification typically varies as per Vineyard Creek.
In 1986 Arroyo Avichi had an overflow channel constructed at Station 0+00'to lead to Baccaglio Basin. The reach of channel below South Novato Blvd toStation 13+50 was dredged in 1996, and on average is dredged about everythree years (liz Lewis, verbal communication).
Arroyo Avichi is unique because it provides medium-sized gravel materialdirectly to the tidally influenced reach of Novato Creek. The lower portion ofArroyo Avichi is also influenced by the tides up to Station 12+07', which isabout 175' upstream of the confluence.
70
Bank CQnditiQnThe lateral extent Qf erQding banks was nQt quantified fQr ArrQYo Avichi.HQwever, dUring the recQnnaissance, measurements were made at discretepoints to determine the extent Qf bank retreat. The ArrQYo Avichi Data areIQcated in the Field Notes in~.
the average of the point measurements fQr bank retreat indicate that bankerosion equals about 3.9'. As in the Qther tributaries, bank erosion appearsto be the predominant process of sediment supply to this channel rather thanbed incision or landsliding. Occasional bank revetments of sackcrete, riprapand CQncrete have been placed 3l0ng the channel. At the extreme upper limitof our reconnaissance we noted that a few inner gorge landslides along theinside bends of the channel were contributing sediment directly to thechannel.
Bankfull GeometIyFigure 22 shQWS three representative cross sections for channel conditions ofArroyo Avichl. The bottom graph is a G4 channel and the middle is an F4. Asin Vineyard Creek a low geQmQrphic bank was Qccasionally measured in thefield and noted in the Field notes. It's cross sectional area was not consistentwith Leopold's (1994) regional curves for bankfull geometry. The hydraulicflow responsible for this low bank is not known. Leopold predicts that thebankfull cross sectional area should be about 36 sq ft, bankfull width should
. equal 18.5' and mean depth should equal 1.9'. Our few measurementssuggested an average bankfull width of 15.5', ranging up tQ 20.5'.
Bed CondIDoD Relatiye to £Qgls. Wood and Sediment StorageFigure 23 shows the pool and woody debris characteristics for Arroyo Avichi.Of the 30 pools greater than l' deep in the study reach, about 67% of thepools were associated with natural features such as bends, bars and bedrock.This is greater than any of the other channels assessed. On the other hand,the 23% of pools associated with wood was lower than other reaches, as wasthe 10% associated with man-made structures. POQI spacing is 302', Qver thetotal distance measured. The middle pie chart shows that 70% of the LWO inthe channel comes from willows, 20% from oak and 10% from bay trees.There were 11 pieces identified. The lower pie chart shows that of the twodebris jams, one crossed the channel and the other was partly blown-out.
O1anneUncisiQn and Adjusnnents in GeQmettyRecent incisiQn of the main Arroyo Avichi appears to average 1.2'. Rates ofrecent tributary incision, like in Vineyard Creek, tends to be greater than inthe main channel. The total amount of incision since the early 1800's has not
71
Arroyo Avichi, Cross Section at 10+90
, 5.00
10.00.......~'-'......c:Cl
'Ql::I:
5.000
0.000-10 -5 o 5 10 15
Distance (ft)20 25
sq ft
30
Arroyo Avichi, Cross SectionTerrace cross sectional area .. 97.5
at 44-47
, 5.00
10.00........t:'-'.... 30.5..c:Cl'v::I:
5.000
0.0000 5 10 15 20 25 30 35 40
Distance (ft)
Arroyo Avichi, Cross Section at 44-47Terrace cross sectional area" 23.7 sq ft
, 5.00
10.00........t:'-'.....c:Cl
'Qj:r:
5.000
FIGURE 22
3025205 10 15Distance (ft)
o-5
0.000 +r.......,....;.;.,~H+-i-i-t-t-t-l~.;..;..t........-t-t-l'"""..............~
-10
Arroyo Avichi Pool and Woody Debris Characteristicsfor Study Reach between 0+00' AND 90-85'
CAUSES OF POOLS GREATERTHAN l' DEEP
10%
1ZI Man-made structures(bridges, concrete, rlpraptransported from bankstablliztlon projects
II1II Wood (tree trunks, roots,woody debris, debris lams)
II1II Other (bends, bedrock,bars, boulders)
• Undetermined
Arroyo AvichiTotal # of pools =30, average pool
spacing =302', study reach distance =9085'.
TYPES OF TREES COUNTED AS LARGE WOODY DEBRISBELOW BANKFULL HEIGHT
Arroyo AvichlTotal # of LWD =11
m Bay Tree
~ Oak Tree
DEBRIS JAM CHARACTERISTICS 0%
Arroyo AvichiOf the total 2 debris jams
IiJ Across channel bed
IIill Partly blown-out
FIGURE 23
been determined. There were a few stations on the lower portions of ArroyoAvichi, such as 4-01' and 36-96', that indicate that portions of Arroyo Avichihave incised a similar 5' as per Novato Creek. Other segments in the lowerportions of Arroyo Avichi seem to follow the same scenario as Vineyard Creeksuch that periods of channel incision, were followed by bank erosion, thenaggradation and continued bank erosion.
We also observed some reaches that had fairly severe erosion problems alongStations 69-00' through 79-50'. This section includes a meander cutoff asseen in Photo 661-62. Bar heights are often as high as 2.5' through this reachand some segments have had bank retreat equal to a bankfull width. Thehorse stables along the upper segment were contributing to water qualitydegradation.
Conclusions for Arroyo AYikhi CreekSignificant coarse sediment, principally from bank erosion, is supplied to theNCFCP from Arroyo Avichi and its tributaries.
SLJN:MARY CONCLUSIONSNovato Creek has the capacity to transport its supplied sediment load fromlocal bank erosion and tributaries to the existing channelization project wherethere, it losses capacity and aggrades its bed. Sediment is predominantlysupplied by channel bank and terrace erosion throughout the entire drainagesystem from the lowland valleys to the headwater tributaries. The ~econdarysource of sediment to the NFCP is from bed erosion of stored sediment withinthe active channel bed. Supply of sediment from the tides, landsliding andsurface erosion is estimated to be orders of magnitude less than the combinedlatter two sources.
With regard to sediment supply the modem landscape has effectively shiftedthe importance of geomorphic processes from mass wasting to fluvial erosion.The entrenched stream network is the product in the tributaries andmainstem Novato Creek from Stafford Dam to the zone of tidal influence. Ifno changes had occurred within the tidal zone, perhaps Novato Creek wouldhave adjusted to transport its increased load out of the system to the bay.With the present scenario of increased runoff and sediment generation in theheadwater reaches, channelization, obstructing railroad bridge ,and loss offunctional tidal creeks and marshland, the tidally influenced system isdestined to aggrade. Overall rehabilitation of the watershed would involvereduction in runoff and large scale restoration of tidal marsh. The feasibilityof applying extensive erosion control to channel and terrace banks throughoutthe entire channel network is impractical.
73
A simplified summary of answers to the initial study objectives are statedbelow, a synopsis of the conclusions is in the Executive Summary.:1) The locations of major sediment sources are pervasive terrace and channelbank erosion throughout the channel network from largest to smallest streamorder.2) The major process by which sediment is being produced and supplied tothe stream system is from fluvial erosion of the channel bed and banks fromflows that are equal to or above bankfull and that have increased infrequency during the last century and a half.3) Change through time and space of sediment sources and landscapeprocesses is indicated by a shift of the most active sites of erosion fromhillsides to the channel network, and from the valley bottom channels to the
, headwater channels. The large high-order channels along the valley bottomsmay have passed through their peak rates of incision and are now aggradingin some restricted areas. Bank erosion, on the other hand, will likely continueuntil the channels are wide enough to form a new floodplain within the
, entrenched channels. The large high-order channels, if left entirely to naturalprocesses, will likely become stable sooner than the headward, small orderreaches, which began to degrade later. .4) There have been large and sudden historical changes in drainage density.The early construction of irrigation and drainage ditches increased drainagedensity in the valleys, whereas the reclamation of tidal marshland decreaseddrainage density within the tidal reaches of the watershed. Since the adventof irrigation, there has been a further increase in drainage density above thetidal reaches due to gullying in the headward rangelands and the addition ofstorm drains in the urbanized lowland valleys. Drainage density has also beenincreased by the incision of alluvial fans that once separated the tributarychannels from the main stem channels.5)Study reaches have been established through this study. These studyreaches should be considered for an ongoing program of locally intensiveempirical observations of the sources and disposition of sediment and watersupplies within the watershed. There should be developed a system ofrepeated observations among these study reaches that would enable a fluvialgeomorphologist to recognize changes in the relative importance of naturalprocesses and land use on sediment and water supplies. Some of the detailsof the required measurements may be provided by this report.
The purpose of an ongoing monitoring program should be to understandinterrelations among upstream and downstream events and processes. Forexample, there needs to be an operational understanding of the feed-backmechanisms between upstream land use or climate change, downstreamgrade change, flooding, dredging and upstream riparian habitat loss.
74
6) The abundance of tidal versus terrigenous sediment increases towards themarsh. Terrigenous sediments probably comprised more than 50% on the1997 volume for the upper 2/3 of the NFCP. Following the 1998 winter, thepercentage from terrigenous sources may be substantially larger all the way.to the NWPRR Bridge.
RECOMMFl'IDATIONS1. Stabilize undercut trees on the high terrace banks before they collapse intothe channel and cause bank erosion to proceed unchecked.2. Consider restoration techniques to divert high velocity flows andassociated high shear stresses away from eroding banks.3. Consider converting more of the diked marshlands into functional tidalwetlands that would dissipate flood flows and increase channel capacity forsediment transport by increasing tidal prism..4. Consider piping urban runoff into a separate and constructed drain systemthat does not connect to Novato Creek but leads separately to a flood controlbasin in the wetlands or to San Pablo Bay. This would effectively reduce theamount of water going into ~e channel, which could reduce flood frequencyand associated damages. Consider that water caught in a basin before goingto San Pablo Bay, could be fIltered by natural vegetation.5. Consider constructing on tributary channels such as Arroyo Avichisediment traps that would funnel some, but not all of the bedload away fromNovato Creek into a separate catchment.6. Reduce the input of fine sediments from cattle trail crossings by fencingthe main tributary channels from cattle access.
75
Atwater, Brian F., 1980, Attempts to correlate Quaternary Climatic theMokelumne River, California, PhD dissertation, University ofDelaware, 214 pp.
Camp Dresser & McKee, Inc., 1983, Novato Creek Flood Control Project,prepared for Marin County Flood Control and water ConservationDistrict. (Survey maps of stream gradient for Preliminary Design areseparate from report.)
Dedrick, Kent G. and Linda Chu, 1992, Draft for Tidal Wate.rways ofSanFrancisco Bay, Historic Widths and Depths on NOS/NOM & USGSTopographic and Hydrologic Swveys, 28 pp.
Dedrick, Kent G. and Linda T. Chu, 1993, Historical Atlas ofTidal Creeks SanFrancisco Bay, California, "Coastal Zone '93, Proceedings of the EighthSymposium on Coastal and Ocean Management", published by AmericanSociety of Engineers, Vol 3, p2464-2478.
Haible, William W., 1980. Holocene Profile Changes along a California CoastalStream, "Earth Surface Processes", Vol S, pp 249-264.
Langbein, W. B. and Leopold, Luna B., 1966 River meanders: theory ofminimum variance; "U. S Geological Survey Professional Paper 422-H".
Leopold, Luna B., 1994, View ofa River, University Science Books, Sausalito,California, 18S pp.
Prunuske Chatham, 1986. Erosion and Revegetation Chapter V in Novato .Creek Flood Control Project enhancement Plan Workbook, prepar-ed forCalifornia State Coastal Conservancy.
Rosgen, David L., 1997, A geomorphological Approach to restoration ofIncised Rivers, "Proceedings of the Conference on Management ofLandscapes Disturbed by Channel Incision", S.S.Y. Wang, E.]. Langendoenand F.D. Shields, Jr. (eds.). ISBN 0-937099-05-8. 11 pp.
Rosgen, David L, 1996, Applied River Morphology, Published by WildlandHydrology, Pagosa Springs, Colorado.
76
Novato Creek-Bank & Pool Conditions: Diablo Blvd to Stafford Dam
o
2900 30002800
u..()a::
2700
-~N'
~I
/·(-~Oct:J I (.
I" =300'
2600
\
2500240023002200
Right Bank
2000 2100
Novato Creek Bank & Pool Conditons, Fall 1997REVETTED BANKS:
sa Cmt Ret Wall
Q Rip Rap[J Sacrete
o shop cartfill rock wallLl bnef; wall
[3 cement slabsill steel pilings
~ wood ret. wall
!ill gablons
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0 ~ ~ 0 0 O~ 0
CHANNEL BED:
Bedrocl< pool
Pool at least l' deep
WCJGd a.::ross lerrace banks
Debris jam
BedrocK bed2000 2100 2200 2300 2400 2500 2600 2700 2800 2900 3000
Left Bank
BANKS:
~ BedrocK
ffiij StablelNatural banks
ERODING BANKS:
~ Below bankfull
• Above & below bankfull
o Above bankfull
~ Eroding bedrock 2000 2100 2200 2300 2400 2500 2600 2700 2800
u..()a:
2900 3000
4000
DOa:in"!,...
3800 390037003600350034003300. 3200
Right Bank
3000 3100
0;; gablons
% cement slabs% steel pilings
~.{,wood wall
o
% cement wall
% rip rapell> Sacrete
% shop cart
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REVETTED BANKS
Novato Creek Bank & Pool Conditons, Fall 1997
CHANNEL BED:
·0 0 0 000 0 0 ¢j i. i' i t 11'1' i.: j iii ,,-,. iii' i i' i" iii' i i 'I • Iii i •••• I' i' '. iii.1 i •• i.' i •• iii. ,"., i' iii
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3900 4000
• 0• i i'" ',". I '. i i •• i
380037003600350034003300320031003000
VVGod 3C;'(,5S terrac.e banks.
DePrisjam
Bedrock bed
Bedrock pool
Pool at least l' deep
4000390038003700
>"5oint\i
left Bank
III Above & below bankfull
0 Above bankfull
~ Eroding bedrock. 3000 3100 3200 3300 3400 3500 3600
11 Hillside erosionlslide
BANKS:
~ Bedrock
lml StablelNaturai banks
ERODING BANKS:
~ Below bankfull
::-
Novato Creek Bank & Pool Conditons, Fall 1997
6000590058005700
I~ =300 I
5500 56005400530052005100
Right Bank
5000
bnck wall
gab10ns
cement slabs
steel pilings
wood ret. wall
REVETTED BANKS:Ba emt Ret Wall
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WJ rock wall
~
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CHANNEL BED:
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Channel Bed
60005900
00 0 0
58005700
o56005500540053005200
o51005000
Wood across terrace banksDllbrisjamBedrock bed
Bedrock pool
Pool at least l' deep
Left Bank
BANKS:
~ Bedrock
~ StableINatural banks
ERODING BANKS:
~ Below bankfull
II Above & below bankfull
o Above bankfull
~ Eroding bedrock 5000 5100 5200 5300 5400
n.oa:
5500
n.:;Eo
5600 5700 5800 5900 6000
•
111 =300'
5000I
4900
,-~
4800470046004500440043004200
Right Bank &a:
4000 4100
Novato Creek Bank & Pool Conditons, Fall 1997REVETTED BANKS:
88 Cmt Ret Wall
Q Rip Rap
II'.l Sacrete
D shop cartfl1i rock wall
[J bnck wall
~ cement slabs
rn steel pilings
~ wood ret wall
mJ gabions
CHANNEL BED:
WOOd acroSS !.errace banksDebrtsjamBedrock bed
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BANKS:
~ Bedrock
~ StablelNatural banks
ERODING BANKS:
f:I Below bankfull
Left Bank a..oa:in
III Above & below bankfull
[J Above bankfull
~ Eroding bedrock 4000 4100 4200 4300 4400 4500 4600 4700 4800 4900 5000
Novato Creek Bank & Pool Conditons, Fall 1997REVETTED BANKS:
Right Bank
7000
, ........" " " " "', , , ," " " " "', , , ," " " " "', , , ,., " " " "', , , ,. """"
69006800
I" =300'
6700
>'3u
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6600650064006300620061006000
~ emt Ret Wall
Q Rip Rap
rrJ Sacrete
0 shop cart
~ rock wall
I:J brick waH
r;;j cement slabs
rn steel pmngs
~ wood ret. wall
fill gabions
CHANNEL BED:
Channel Bed
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Pool at least l' deep
Wood across lerrace bankEDebris jam
Bedrock bed6000 6100 6200 6300 6400 6500 6600 6700 6800 6900 7000
BANKS:
~ Bedrock
ml StableINaturai banks
ERODING BANKS:
~ Below bankfull
Left Bank
II Above & below bankfull
[] Above bankfull
[; Eroding bedrock 6000 6100 6200 6300 6400 6500 6600 6700 6800 6900 7000
8000790078007700
1" "300'\
7500 76007400
a.:Eo
73007200
Right. Bank
7000 7100
Novato Creek Bank & Pool Conditons, Fall 1997REVETTED BANKS:
§§I Gmt Ret Wall
o Rip RapEi1 Sacrete
o shopcart .~ rock wall
[3 brick wallIZI cement slabs[]] steel pUingsa wood ret wall~ gabions
CHANNEL BED:
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~ Bedrock pool
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litII
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Left Bank .
BANKS:
!!! Bedrock
eJ StablelNatural banks
ERODING BANKS:
~ Below bankfull
• Above & below bankfull
E3 Above bankfull
II eroding bedrock 7000 7100 7200 7300 7400 7500 7600 7700 7800 7900., I
8000
..., ~
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\, ~,
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Novato Bank & Pool Conditons, Fall 1997\l
REVETIED BANKS:
~ Gmt Ret WallRight Bank
0 Rip Raap 0..
~ SacTete uII:
0 shop cart in
~ rock wall
0 brick wall
lZl cement slabs
ITl steel pilings 8000 ,8100 8200 8300 ___8400 __ _8~OO~~_ JH~_QQ___ 8700 8800 8900 9000E3 wood ret. wall
m gabions
CHANNEL BED:
@ Bedrock pool
0 Pool alleasl l' deep Channel Bedf.!t .f/. ;:- ..~~ ·ff'·,' j; I :1; ~:::,r~;·:::·.d; Hf·"t\
• Wooo across terraC8 banks (J) 0 ~),( Debris jam
;. Bedrock bed~ 8000 8100 8200 8300 8400 8500 8600 8700 8800 8900 9000
BANKS:
~ Bedrock
m StablelNatural banks
ERODING BANKS: Left Bank~ Below bankfull
• Above & below bankfull
[] Above bankfull
~ Eroding bedrock 8000 8100 8200 8300 8400 8500 8600 8700 8800 8900 9000
I;:)Q
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Novato Creek Bank & Pool Conditons, Fall 1997 }{ ~b--'
REVETTED BANKS: I
B8 Cmt Ret Wall Right Bank "I :.300'Q AipAap
fl] Sacrete
0 shop cart
~ rock wall
E:J bnck waH
EJ cement slabs
III steel pilings 9000 9100 9200 9300 9400 9500 9600 9700 9800 9900 10000~ wood ret. wall
~ gabions
Wood across terrace banksDebris jluTl
Bedrock bed
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Channel Bed .3
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~ Bedrock poolo Pool at least l' deep~ "-.:1~>·:~~! w!;-r!!:"': r,;::.~·;j;:!~;;i Hf..i;:
•1
9000 9100 9200 9300 9400 9500 9600 9700 9800 9900 10000
left Bank
BANKS:
~ Bedrock
18 StablelNatural banks
ERODING BANKS:
f.3 Below bankfull
II Above & below bankfull
[J Above bankfull
~ Eroding bedrock 9000 9100 9200 9300 9400
Doa:bT""
9500 9600 9700 9800 9900 10000
120001190011800
~,
I
"'=300'
11600 117001150011400113001120011100
Right Bank
11000
Novato Creek Bank & Pool Conditons, Fall 1997REVETTED BANKS:
B8 Gmt Ret Wall
Q Rip Rap
Ir1 Sacrete
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LJ brick waH~ cement slabs
ill steel pilings
~ wood ret. wall
lID gablonsQ)OJ"0.;::
~ou....><:o:tChannel Bed ~
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CHANNEL BED:
~ Bedrock poolo Pool at least l' deapEf7.~ :':'1.-.../.: \,":;:';~:', L·:::ij:J~.-;jj ik.',ri
• Wood across terrace banksX Debrisjam
~ Bedrock bed
11000 11100 11200 11300 11400 11500 11600 11700 11800 11900 12000
BANKS:~ Bedrock
~ StableINatural banks
ERODING BANKS:
8 Below bankfull
Left Bank
120001190011800
IIIa.oa:in
1170011600115001140011300112001110011000
Above & below bankfull
Above bankfull
Eroding bedrock
Hillside erosionlslide
•
111:= 300'
I •
10900 110001080010700
gn.m
106001050010400103001020010000 10100
Right Bank
Novato Creek Bank & Pool Conditons, Fall 1997REVETTED BANKS:
Ba Gmt Ret Wall
Q Rip RapfX) . Sacrete
o shop cart
~ rock wallE:J brick wall
r.J cement slabs
ill steel pWngs§ wood ret. wall
~ gabions
CHANNEL BED:
~ Bedrock pool
0 Pool at least l' deepChannel Bed3i ~:VL:;".::: ~'::;;':l! i b.;:',i lj::n...iH f!::::""'l
• Wood across terrace banks
¢1 Debris jam 0 CD 0 0Bedrock bed
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10000 10100 10200 10300 10400 10500 10600 10700 10800 10900 11000
BANKS:
~ Bedrock
!ill StablelNatural banks Left BankERODING BANKS:· n.~ Below bankfull
0II:fu
II Above & below bankfull
t] Above bankfull'.
~ Eroding bedrock 10000 10100 10200 10300 10400 10500 10600 10700 10800 10900 11000
1300012700 12800 12900126001250012400123001220012100
Right Bank
12000
Novato Creek Bank & Pool Conditons, Fall 1997REVETIED BANKS:~ Cmt Ret Wall
Q Rip Raprf] Sacrete
o shop cartIillI rock wallLJ bnck waH
Q cement slabsrn steel pilings
~ wood rat. wallBJ gablons
CHANNEL BED:
~ Bedrock poolo Pool at least " deep~: ::",""' . ,,';C:, \~': :·,.::;'::j;_;L:_:~ ~i::.'J·.
• Wooa across ierrace banksX Debris jam
~ Bedrock bed
Channel Bed'ECD
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12000 12100 12200 12300 12400 12500 12600 12700 12800 12900 13000
BANKS:
gJ Bedrock
rB StablelNaturai banks
ERODING BANKS:
~ Below bankfull
Left Bank
II Above & below bankfull
o Above bankfull
~ Eroding bedrock 12000
!&1 Hillside erosionfslide
12100 12200 12300 12400 12500 12600 12700 12800 12900 13000
13'9001380013700
•
1360013500134001330013200
Docr..,.
13100
Right Bank
13000
Novato Creek Bank & Pool Conditons, Fall 1997REVETTED BANKS:
E8 Gmt Ret Wall
Q Rip RapffJ Sacrete
o shop cart
ffiJ rock wall
LJ bnc!<: wall
[;l cement slabs
rn steel pilings
~ wood ret. wallfB] . gablons
CHANNEL BED:
~ Bedrock poolo Pool at least l' deep~ ~.'i: ..:<: \·.... n;-€iJ'l r:·~~rli.::·~); ;!.::~".
Wood across terrace banKSDebris jam
Bedrock bed
CD.g>1::lD
Channel Bed £~
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13000 13100 13200 13300 13400 13500 13600 13700 13800 13900 14000
BANKS:.~ Bedrock
. @ StablelNaturai banks
ERODING BANKS:
~ Below bankfull
Left Bank
II Above & below bankfull
o Above bankfull
Bl Eroding bedrock 13000
r±1 Hillside erosionlslide
13100 13200 13300 13400 13500 13600 13700 13800 13900 14000
16000159001580015700
I" ==-300 1
156001550015400153001520015100
Right Bank
15000
Novato Creek Bank & Pool Conditons, Fall 1997REVETTED BANKS:
ES Cmt Ret Wall
Q Rip Rap[;[) Sacrete
o shop cart
[email protected] rock wall[J DrlCf~ wai'
Q cement slabsill steel pilings
bI wood ret. wali1m gablons
BedChannel
Q)Cl"0
~e'5en
li?i'iii"i'i"iii~ii'ilii'iiii?'??ii'i'l'?'iii'il"i"iiiil.tiiiiiili?i~iiiiiliiii?il.....115000 15100 15200 15300 15400 15500 15600 15700 15800 15900 16000
• Woad across terrae<' banKS
X Deprisjam
~ Bedrock bed
CHANNEL BED:
~ Bedrock pool
Q Pool at least l' deep':: :";"..:t"
BANKS:~ Bedrock
ill StablelNatural banks
ERODING BANKS:
r:l Below bankfull
Left Bank
• Above & below bankfull
o Above bankfull
~ Eroding bedrock 15000
fi1 Hillside erosionlslide
15100 15200 15300 15400 15500 15600 15700 15800 15900 16000
Novato Creek Bank & Pool Conditons, Fall 1997REVETTED BANKS:
~ emt Ret Wall
Q Rip Rap
fX] Saarete
0 shop cart
~ rock wall
I:] bnc\~ waH
Ed cement slabs
ill steel pilings
~ wood rat. wall
lID gaolons
Right Bank
T'H+T7'T'... I .... I .. ,
14000 14100 14200 14300 14400 14500 14600"
14700 14900
• 'f--FL..OW
'''=300'
15000
j iii i J' iii I' i. it. i •• i i ••• i" i' iii. i.' ... iii iii i.I" i. i i 'I iii. J i ••• iii iii i' i' i' i' iii. i i.' iii. iii '. i •• i I
14200 14300 14600 15000
o1490014800
00 0
14700
00oo14500
o14400
ooo
Channel Bed
14000 14100
'NooO across ierrace DanksDebris jam
Bedrock bed
CHANNEL BED:
~ Bedrock pool
\2 ~~~Ia:~:~ l·..dee~ ":.,_.
BANKS:"K;} Bedrock
~ StablelNarurai banks
ERODING BANKS:
f:'I Below bankfull
left Bank t::~'5u
~,....
(I Above &below bankfull
. Q Above bankfull •
~ Eroding bedrock 14000
~ Hillside erosionlslide
14100 14200 14300 14400 14500 14600 14700 14800 14900 15000
1800017800" "17900
I" ~.300'
17600 1770017300+ "1740017200
Right Bank
17000 17100
Novato Creek Bank & Pool Conditons, Fall 1997
REVETTED BANKS:~ Cmt Ret Wall
Q Rip Rap[[l Sacrete
o shop cart§ rock wall
EJ briCk waH
EJ cement slabs
rn steel pilings
~ wood ret. wall
o gabions
Wood across lerrace banksDebris jam
Bedrock bed
Channel Bed
i : ! ; I
il"'i""""""I""",?""?"",S,?,,?,,,,~,,?,9,,P"""?",?"",i",?,y",,,
CHANNEL BED:
~ Bedrock pool
Q Pool at least l' deeps: ....::/._:,/; ':.'i'{;"::;. ~;(..;: :i<i-:..iij !!V\ii
•X~
17000 17100 17200 17300 17400 17500 17600 17700 17800 17900 18000
BANKS:
~ Bedrock
1m StablelNatural banks
ERODING BANKS:
~ Below bankfull
II Above & below bankfull
D Above bankfull
B;j Eroding bedrock
Left Bank
17000 17100 17200 17300 17400 17500 17600 17700 17800 17900 18000
\~ "0 0°~..... 0- ,IX,
Novato Creek Bank & Pool Conditons, Fall 1997 /•
REVETTED BANKS:
~ Gmt Ret WallRight Bank ,u "300'
Q Rip Rapfi:j Sacrete
0 shop cart
~ rock wall
LJ brick wall
EJ cement slabs
OJ steel pilings 16000 16100 16200 16300 16400 16500 16600 16700 16800 16900 17000~ wood ret. wall
lm gabions
CHANNEL BED:
~ Bedrock poolChannel Bed0 Pool alleast l' deep
@1 ::1'':::'''.::: ....·;;I<~H: :';:;:-..~;~:iU;~ H::N(
• Wood across terrace banks iI i CoX Debris jam 0, b ~~~t)~
~ Bedrock bed ~ i i
16000 16100 16200 16300 16400 16500 16600 16700 16800 16900 17000
BANKS:
~ Bedrock
§ StableINatural banks Left BankERODING BANKS:flI Below bankfull
II Above & below bankfull
0 Above bankfull..
~ Eroding bedrock 16000 16100 16200 ~6300 16400 16500 16600 16700 16800 16900 17000
Novato Creek Bank & Pool Conditons, Fall 1997
2000019900I'
1980019700I
1960019500194001930019100
Right Bank
19000
~ % cement wall
~ % rip rapEl % Sacrete
o % shop cart!ill % rock wall
o ':'~ bncf: wan
[2j % cement slabs
m % steel pilings
El % wood wall
~ % gablons
REVETTED BANKS
CHANNEL BED:
WoOd across lerracE: banksDebris jam
Bedrock bedIii 1 i j I ," iii iii i' iii iii' i'" .'. iii
Channel Bed
2000019900
,o >K 0
I
19800I' iii I iii. iii.' Iii' iii' iii
19700
,
oo19500 19600
00
19400Iii i, I' iii I'" iii I i iii Iii Ii. I i 11 iii ii"
10
1930019200
00
19100
o19000
~ Bedrock pool
o Pool at least l' deep
~.
•>f-i';,J
20000
"0>r::0,,0>r::r::mr::.om~£r::0>
19900
"0>r::o,,r::0>mr::.or::m~r::OCl0>
19800197001960019500194001930019200
Left Bank
BANKS:
~ Bedrock
o StablelNatural banks
ERODING BANKS:
~ Below bankfull
• Above & below bankfull
0 Above bankfull
~ Eroding bedrock 19000 19100
rt1 Hillside erosionlslide
• I"
18800 18900 19000
I d =300'
18300 18400 18500· 18600 1870018100 18200
Right Bank
Novato Creek Bank & Pool Conditons, Fall 1997REVETTED BANKS:
B8 Gmt Ret Wall
Q Rip Rap~ Sacrete
o shop cart
lliI rock wall
Ll brick wall
Q cement slabs
m steel pilings
~ wood ret. wall
f¥J gabions
Wood across terrace banksDebris jam
Bedrock bedi" iii iii. i i •• j i'. iii" i i.i •• iii iii.' i' iii. Iii' i' iii i' i I' iii I" iii. iii Ii. iii' i •• i':;. I
Channel Bed
,
q 0Ii. iii •• i. j."
18900 1900018800
IIICl
"~.!2
; 0 X 0 ¢ ~ 0 000 I18200 18300 18400 18500 18600 187001810018000
CHANNEL BED:
~ Bedrock poolo Pool at least l' deepa.f ;:;il:.;,.:·j w:r"::r; t·r:i~;J':;~!ji H:::;,,/
IIilX~
BANKS:
~ Bedrock
rID StableJNaturai banks
.ERODING BANKS:
rA Below bankfull
Left Bank
II Above & below bankfull
[3 Above bankfull
~ Eroding bedrock 18000 18100 18200 18300 18400 18500 18600 18700 18800 18900 19000
Novato Creek Bank & Pool Conditons, Fall 1997
,2200021900218002170021600
1"::.300'
\
2150021400213002120021100
Right Bank
21000
% cement wall
% rip rap
% Sacrete
% shop cart
% rock wall
~'C bnc:l'; wall
% cement slabs
% steel pilings
% wood wall
% gabions
REVETIED BANKS
CHANNEL BED:
Channel Bed
i Iii' ': :OX 00 POX. 00 ! 0 0i I I ~ i , iii I iii • I I Iii Iii iii iii iii I : I \ I i I I iii I :. I I Ii' J iii iii ii' iii I Iii' ii" ii' i • i i • iii i , , 'i' , i I Iii iii i , , , I
2200021900218002170021600215002140021300212002110021000
Woc,d across terrace banksDebris jam
Bedrock bed
Bedrock pool
Pool at least l' deep
(!f.(.~.\\'i(q)
o~:
BANKS:
~ Bedrock
IT;:] StablelNatural banks
ERODING BANKS:
~ Below bankfull
Left Bank
• Above & below bankfull
0 Above bankfull
~ Eroding bedrock 21000
rf1 Hillside erosion/slide
21100 21200 21300 21400 21500 21600 21700 21800 21900 22000
Novato Creek Bank & Pool Conditons, Fall 1997
I" =300'
210002090020800I
20300 20400 20500 20600 20700
Right Bank
I ••••••
20000 20100 20200
REVETTED BANKS
~ % cement wall
B % rip rapB %Sacrete
o % shop cart
§ % rock wall
o % brick wall
o % cement slabs
ill % steel pilings
8 % wood wall
ml % gabions
CHANNEL BED:
'i iii i' iii i i' iii iii., J ••• i it j' (I iii I'. i.'. i' i'. I. "1 i •• t, i t 1. itt t., t t t",.,. i' I." .• i 'I
20000 20100 20200 20300 20400 20500 20600 20700 20800
Channel Bed~ Bedrock pool
o Pool at lBast l' deep~ ~·y._ ...!t; Vf:!: ,;:. :··;::~;:':.::.:ji ;;(:1[/
II Wood across terrace banks¥ Debrisjam~ Bedrock bed...
o o o o ~X o i tX li
t i fi 1 !
• i' I ii, •• i.' j i I
20900 21000
BANKS:
~ Bedrock
!8 Stable/Natural banks
ERODING BANKS:
~ Below bankfull
Left Bank
1& Above & below bankfull
0 Above bankfull
~ Eroding bedrock 20000 20100
~ Hillside erosionlslide
20200 20300 20400 20500 20600 20700· 20800 20900 21000
Novato Creek Bank & Pool Conditons, Fall 1997
Right Bank1"="300'
I
23900 24000238002370023600
j
23500I
23300 23400232002310023000
REVETTED BANKS:B8I emt Ret Wall
El Rip Rap[:J Sacrete
o shop cart§l rock wall
Cd bnck. wall
o cement slabs
rn steel pilings
B wood ret. wall
[J gabions
CHANNEL BED:
Channel Bed
24000239002380023700
ex1 ,., i i' iii" 1'1 iii iii'. iii i' iii'. iii I Iii' • I I
23600235002340023300232002310023000
Wood across terrace banksDebris jam
Bedrock bed
Bedrock pool
Pool at least l' deep
BANKS:~ Bedrock
!ilil StablelNatural banks
ERODING BANKS:
~ Below bankfull
Left Bank
III Above & below bankfull
o Above bankfull
~ Eroding bedrock
~ Hillside erosionlslide
23000 23100 23200 23300 23400 23500 23600 23700 23800 23900 24000
In = "!DO'
22900 23000• I
22300 22400 22500 22600 22700 22800
Right Bank
22000 22100 22200
Novato Creek Bank & Pool Conditons, Fall 1997
REVETTED BANKS:
I!8l Gmt Ret Wall
EJ Rip Rap
[J Sacrete
o shop cart
fill rock wall
Q brick wall
IZJ cement slabs
m steel pilingsB wood ret. wall
ran gabions
CHANNEL BED:
Bedrock pool
Pool at least l' deep
WoOd across ierrace banksDebrisjarn
Bedrock bed
Channel Bed
Bowman Creek
0:»: 10< 0 !~ I f!h 6* L1i ' •••*.,,i ' ••• , • , • , , • ~. I • ,~, ••• , •• , • , I ••• i •••• , ' ••• i •••• i • I •• , • , •• i ' •• , I •• , ,1, I , , • , ' •• I , ii, I ,1, •• , I !
22000 22100 22200 22300 22400 22500 22600 22700 22800 22900 23000
Bowman Creek
Left Bank
BANKS:
~ Bedrock
10 StablelNatural banks
ERODING BANKS:
~ Below bankfull
II Above & below bankfull
o Above bankfull
~ Eroding bedrock
~ Hillside erosionlslide
22000 22100 22200 22300 22400 22500 22600 22700 22800 22900 23000
Right Bank ~ '-- 1"_=_3_00_' ----..3=--.1
E~
,24000 24100 24200 24300 24400 24500 24600 24700 24800 24900 25000
Novato Creek Bank & Pool Condltons, Fall 1997
REVETIED BANKS:Il8I emt Ret Wall
EJ Rip RapCI Sacrete
o shop cart~ rock wallCd brick wall
~ cement slabs(J] steel pilings
8 wood ret. wall
rn gablons
CHANNEL BED:
Wood across terrace oanksDebris jam
Bedrock bed
~ Bedrock pool
o Pool at least ,. deep
"'":;;.,
•>f-~~
Channel Bed
oI" iii ii' i I'.' iii l' i' i' " Iii i' iii: i' i 'i' 1 Iii i' iii" I I " iii iii Iii i I I
24000 24100 24200 24300 24400 24500 24600
:
aU«iii Iii. I I" 1 ii' 1: iii I. iii iii iii iii
24700 24800 24900 25000
BANKS:~ Bedrock
E::I StablelNatural banks
ERODING BANKS:
~ Below bankfull
Left Bank
II Above & below bankfull
o Above bankfull
r;a Eroding bedrock 24000 24100 24200 24300 24400 24500 24600 24700
!i1 Hillside erosion/slide
. 24900 25000
25900 26000
I =::JVV
• I
25700 25800
25700 25800 25900 26000
E~3=1IIC\1.Qore="0_::] .... 1II00:.a..1i1llu-;=a::(/)=
- a.Ill(/)
~tb XO I; II i l
• i' iii i •• i. i' i i'" iii:'. i , ••• 1 iii iii
.,.,', .,, , , ", , , ," " ", , , ,." " ", , , ," " ", , , ,
••• 1"
8::tJ
a..Ua:
_----. 0~ t='l..ouJ::IIIen
.mI----------------.;=-------~-----'
E::]oa..U
o 0 0 6 ¢ 0; 1
Ii ••• iii J' iii: i.'. iii: iii' i i. Ii •• i I •• i i t. I i'l til. J' Iii iii •• iii i i
Channel Bed
Right Bank
25000 25100 25200 25300 25400 25500 25600
25000 25100 25200 25300 25400 25500 25600
CHANNEL BED:
• Wood across terraCE: banks
>i Debris jamIt- Bedrock bed)
Novato Creek Bank & Pool Conditons, Fall 1997
REVETTED BANKS:BBI Gmt Ret Wall
EJ Rip RapQ Sacrete
o shop cart
18 rock wallQ bric~; wall
o cement slabs
m steel pilings
B wood ret. wall
f12I gablons
~ Bedrock pool
o Pool ,at least l' deep~ /;'", ..:; ,..: ."",. : ':':';""";; :;,~',I",
Left Bank
BANKS:
~ Bedrock
~ StablelNatural banks
ERODING BANKS:
~ Below bankfull
II Above '& below bankfull
rJ Above bankfull
~ Eroding bedrock
~ Hillside erosionlslide
25000 25100 25200 25300 25400 25500 25600 25700 25800 25900 26000
Novato Creek Bank & Pool Conditons, Fall 1997
~
- §
~ ~ !: ~ Tl r ~ I ~~FLoW
~----~- .1".;:300'
REVETTED BANKS
~ % cement wall[j % rip rap
E9 % Sacrete
o % shop cartIDl % rock wallo ~<~ br:ck \Nai!
I2l % cement slabsrn % steel pilings
EI % wood wallQ % gaololls
Right Bank
o 100 200 300 400 500 600 700 800 900 1000
1000900800700600500400
; I 1\
o KX.· I dix:;x I ..1.. . . Ij
300200
Bed
o100
Q)01U
~o:is
BChannel
~o
Debris jam
Bedrock bed
v\iooci aCfC:SS terrace banks
Bedrock pool
Pool at least l' deep
CHANNEL BED:
BANKS:
~ Bedrock
B StablelNatural banks
ERODING BANKS:
~ Below bankfullLeft Bank
II Above & below bankfull
[] Above bankfull
~ Eroding bedrock 0
l'±'! Hillside erosion/slide
100 200(
300 400 500 600 700 800 900 1000
I
• - 2,000
2000. I'
19001800
1"=300'
1600
\
1500140013001200
Right Bank
••• I
1000 1100
Novato Creek Bank & Pool Conditons, Fall 1997
REVETTED BANKS:
~ Gmt Ret WallQ Rip RapfX:l Secreteo shopcart§ rock wallo ::;f!C~ ii2H
r:d cement slabsrn steel pilingsbI wood ret. wall[ill gab'Q!:~
CHANNEL BED:
I j' iii 1 •• iii. iii" i 'II. iii i i» iii iii iii. iii i •• iii i i f iii iii: •• i •••• i' j" iii •• i' I •• i •••• i' i •• i' iii i" iii
Channel Bed
20001900
<D 00
1800
00
17001600150014001300120011001000
Debris jam
Bedrock bed
Bedrock pool
Pool at least l' deep
BANKS:
~ Bedrock
~ StableINatural banks
ERODING BANKS:
f:l Below bankfullLeft Bank
II Above & below bankfull
D Above bankfull'.
I§l Eroding bedrock 1000 1100 1200 1300 1400 1500 1600
lJ UndIfferentiated
1700 1800 1900 2000
Novato Creek Field Reconnaissance NotesAbove Diablo Ave Bridge
4/11/97, Laurel M. Collins
METHODS AND SfANDARDS:-Station 0 is located at the upstream (USf) edge of Diablo Ave Bridge.This section of channel is not influenced by tidal flow.-Field note stations are reported as negative values, in standard Englishunits, from the zero point at Diablo Bridge. They are written in swveynotation. For example, 1-06 and 13-26 are equal to 106 and 1,326 feetupstream (UST) of Diablo Bridge, whereas 5+25 would equal 525 feetdownstream (DSf) of the bridge.- Distances UST from Diablo Bridge were measured by pulling a 300'fiberglass tape along the length of Novato Creek UST to Stafford Damspillway.-All references to left bank (LB) and right bank (RB) are standardized tolooking toward the DST flow direction.- References to average particle diameter (D50) are given in millimeters(mm).- Width and depth measurements were made with either a telescopingswvey rod or a measuring tape during a level line swvey of crosssection. Measurements are referenced to flow at bankfull (BKFL) stage.The reported amounts of undermining and/or bank erosion aremaximum amounts at a discrete point unless otherwise noted.- Photo references in the field notes include order number for the photoalbum (shown in the green squares in the Photo Album 1), roll number(R#) and photo negative number (P#). All photos that wereaccompanied by field notes are labeled for their roll and negativenumbers on their back side. Negatives are located at consultant's office.Photographs in the album also include early photographs from .unidentified individuals and black and white xerox copies of picturesfrom the 1987 Novato Creek Erosion Control Feasibility Study byStuber-Stroeh Assoc., Inc.-Tree number (#) refers to trees that were previously labeled in thefield by the MCFCD. New tags were placed on trees that had significanceto this study regarding their age and elevation relative to the bankfullstage and terraces. They are referred to as Tag numbers rather thantree #.
Abbreviations include:BDRK - bedrock
1
CA - cross sectional areaeMF - corrugated metal pipeD50 - Diameter of average particle size in gravel bars, excluding sand
which is less 2 mm.Dbf - mean depth of bankfull flowDBH - Diameter of tree at breast heightDmn - mean depth at bankfull stageDmx - maximum depth, measured at thalwegDSf - downstream .ER - Entrenchment Ratio which equals the flood prone width divided by
bankfull width.LB - left bankPVC - Polyvinylchloride pipe.RB - right bankRSC- Rosgen Stream Classification (Rosgen, 1996)RCP - reinforced concrete pipeUST - upstreamWbf - width of bankfull flowWDR - width to depth ratio which equals the bankfull width divided by
the mean depth.Wfp - width between banks at two times the maximum depth at
bankfull flow.WS - water surface
DistanceStation(feet)-0+100 Photo 24 Album I (R3P1) looking DST from Diablo Ave
Bridge at new, 1996 rip rap project on the LB and older sacretewall on the RB.
0-0 Photo 26 (R3P2) looking UST from DST end of Diablo Bridge.Note the two cement sills at each end of the bridge that maintainchannel gradient but impede fish migration during low flow.Flow capacity within the bridge does not appear to be impededby sediment storage.
1-06 Photo 27 (R3P4). An approximately 17" steelhead istrapped in the long pool just USTof the grade control sill at theUST edge of Diablo Blvd Bridge. Numerous smaller fish, includingfry, are noted in the pool. Silt is more prevalent in this stretchthan DST of the bridge or UST of the debris jam at 4-27'. Theterrace banks are very silty in this segment and bank erosionalong this reach is increasing the local supply of fine sediment.
"
2
Two culverts are present at RB: a 1.8' box and l' RCP.Photo 28 (R3P6), looking UST at RB erosion along outside bend ofthe creek (in background of photo).
3-38 Photo 29 (R3P7), looking UST. Orondo, a non-nativeinvasive vegetation, is located on RB (right center of photo) Aleaning willow, at 4-27, is impeding flow (center of photo).
3-70 Willow # 291 is in the channel at this station.4-27 Photo 30 (R3P8), looking DST at debris jam that was formed
by a leaning willow.5-34 Photo 31 ,(R3P9), looking UST at lateral gravel bars. The
channel appears slightly aggraded as compared to segmentsdownstream of the debris jam at 4-27. The D50 of the bar is ""'17 mm. According to the MCFCD channel survey of 1985, the bedelevation near this point would coindde with the top railing ofthe railroad bridge. This means that the water surface slope ofbackwater from the railroad bridge that occurs during very highflood flows could extend this far back into the channel. Evidenceof sedimentation suggests the possible effects of backwater tothis vicinity. According to the MCFCD survey the terrace banksare also at their lowest about 80' downstream of here. whichwould be the point of imminent flooding during the 33,000 cfsdischarge event.
7-21 Photo 32 (R3PI0), looking UST at partially blown-outcement weir or old sewer crossing. Note sediment accumulationbehind structure.
7-66 Photo 33 (R3Pll), looking at RB bay tree #229. Minor bankerosion has exposed two distinct root layers that have madetwo distinct banks. One at 3.77' and the other at 1.64' above thebed. RSC=G4
7-79 l' CMF8-01 Willow tree #270 down in channel.9-00 Photo 34 (R3PI2), looking at tree #209 with berries and
branches piled behind it. A crude estimate of growth rings givesan approximate age of 50 years. Its diameter is 2.25'. In general,the section from 1-00 to here has banks that-are typicallycovered with berries and are not commonly raw from bankerosion. There is good riparian shading, unlike many of thereaches below Diablo Bridge where channelization has takenplace.
9-67 Willow growing in channel, impeding flow.9-87 Willow growing in channel, impeding flow. A large LB bar
is 3.2' high above WS. -
3
10-42 Photo 35 (R3P13), looking UST at partially raw, eroding RB(person with rod in photo is standing at 10-88). The terracebanks are predominantly fine silts and sands.
11-75 Undermined oak tree. The height from the bed to the trunkbase is 5.9'. Bank erosion = 4'.
12-70 Photo 36 (R3P14), looking DST at LB bay tree #262, that isstarting to pull from the bank. Average bank erosion = 5.9'.Sand is more abundant in the bed here than in downstreamreaches. Note that shading has precluded vegetative growth on .the channel bed.
12-75 Average bank erosion II:: 4'.13-13 Wide section ends and channel becomes much narrower.
DSO is about 7 nun.13-88 Sediments appear more embedded here than the DST reach.~=~ .
14-82 Photo 37 (R3P15), looking at tree # 328. Bank erosion =3.9'.
-16-00 Photo RI0P7 (missing), looking DST at level line survey attree #343. See Cross Section Survey at 1600, Figure 17A inrepone
16-01 Channel type changes from G4 to F4 RSC17-53 Photo R10P9 (missing). l' RCP on LB.17-76 Photo 38 (R3P16), looking at RB erosion = 4'. Note the
proximity of the building to the edge of the bank.18-69 RB erosion =4' at bay tree # 468.19-44 Poplar tree # 412.19-42 LB culven hidden by vegetation. This site is near the Dept
of Motor Vehicles building.21-57 Photo 39 (R3PI7), looking UST at RB erosion.21-71 Photo 40 (R3P18), looking UST at 7th St Bridge. RSC may
change in here. Note the densely vegetated bar on the LB (rightside of photo).
23-07 The channel bed has coarse gravels that are being buriedby fmes.
23-70 Channel bed is mostly sand and fine gravel.24-46 LB bar is inhibiting flow on downstream end of 7th St
Bridge.24-60 DST edge of 7th Street Bridge has a pool that has formed at
the end of the concrete bed underneath the bridge. The heightof the box beneath the bridge is 9.5'. There is a 3' RCP at LB.
25-27 UST edge of 7th St Bridge. There is abundant sandupstream of the bridge. A LB willow growing in the channel isimpeding flow under the left side of the bridge. The willow
4
should·be removed, but could be used for bank protectionelsewhere.
26-08 Photo 42 (R3PI9), looking usr at the fonner USGS gage.26-64 Location of stream gage.27-00 RSC = G427-58 RB undercut 5'.27-84 I'RCP. In this reach the sands and gravels appear to have
same proportion offmes as observed in lower Bowman Cr.28-49 Photo 43 (R3P20), looking usr at massive bay tree roots
that have slumped down along bank at 28-88.29-08 UST edge of library footbridge.29-19 l' RCP LB.30-00 Photo 44 (R3P21), looking DSf at RB rip rap and undercut LB
bay tree. From here to some distance upstream, there is abundantsand deposition.
30-96 Pool due to narrowing and lateral bar, and possibly due tobackwater effect of downstream sand deposition.
32-52 LB 30" CMP33-00 Photo 45 (R3P23), looking DST at eroding banks near
structure. Note that much of the rip rap has been redistributed.Photo 47 (R3P23), looking UST at relatively natural lookingbanks. Lots of sand noted in channel bed.
33-75 RB erosion = 9.3'.33-95 0.5' PVC.34-29 RB erosion = 2.0'34-97 Bridge abutment pier.36-00 Photo 48 (R3P24), looking toward LB. DST edge of foot
bridge with concrete base in channel bed. LB erosion = 4.6'.37-47 Bay tree across terrace banks.38-23 RB willow slumped into channel and growing across bar.38-76 Very sandy reach.39-24 RB 15" CMP.39-56 RB bank erosion = 4.9'. roots and bedrock POOl present in
channel.39-187 Photo 49 (R3P26), looking DST at RB oak tree that is
growing within the terrace banks. This tree may have slumped.39-99 Photo 50 (R3P25), looking DST at Bank erosion = 4.6'.
Upper terrace height above bed = 10.8' Height of oak tree abovebed = 8.2' DBH = 2.7'. Height of oak tree below terrace = 2.6'
41-44 Photo 51 (R3P27) looking DST at cross section.RSC = F4LB and RB erosion = 7.2'Upper terrace height above bed = 11.3'
5
Height of oak tree above bed = 6.7' DBH =2.9'Height of oak tree below Terrace =4.6'.
41-54 RB 15" RCP.42-10 Photo 52 (R3P28), looking USf at Grant St bridge. Note silt
stone terraces deposits exposed in pool bottoms at this location.43-24 DSf edge Grant St Bridge.43-94 DST edge of foot bridge and wall abutments.44-56 Photo 53 (R3P29), looking DST through the Grant Ave box
culvert. This station = usr edge of foot bridge at Grant Ave.Note the deposition of gravels on the RB of box culvert. Thecapadty of the box culvert has been diminished by about 22%.The way the box culvert meets the stream at an angle hasaugmented sediment deposition within the box.
45-20 Pool due to narrow channel and RB bar.45-31 Photo 57 (R3P30 & 31), looking DST at willow on lateral bar
that is growing within the CAbf. The tree probably slumped downas part of the ongoing RB erosion, which = 16 to 20'. DBH = 2.9'
46-30 RB erosion =3.6'. Pool formed by boulder.46-64 Photo 60 (R3P32), looking usr at roots exposed by bank
erosion and pools formed by boulders. The boulder in thebackground, next to person standing in picture is at this station.RB erosion = 3.2'
48-00 The RSC appears to be in transition between F4 and G4.Bank erosion = 5'.
48-88 Photo 63 (R3P33), looking at a private fence line that isbeing undermined
49-11 Photo 67 (R3P34), LB erosion = 11.2' beneath bay tree atoutside bend of channel. Note sand deposition on point bar oninside of bend. This may be coming from USf bend erosion shownin photo R3P36.
51-00 Photo 70 (R3P36), looking DST at eroding RB on outside ofbend near structure.
Photo 71 (R3P35), looking USf at rip rapped RB.52-25 Constricted section of channel due to willow branches and
large bay tree trunk.52-39 LB PVC = 5".53-66 Photo 75 (R3P37), looking UST at new retaining structure on
RB. Note height of point bar in center portion of photo is 4.6',higher than other bars observed so far.
54-00 New erosion around LB cement walls shown on the centerright portion of photo R3P37.
54-55 Photo 76, (R5P11). Gravel bar height along steel-piling (1-beams) retaining wall =4.6'.
6
54-97 LB l' RCP.56-27 Section of bank on the outside of bend, between retaining
structures, will be likely loci of future erosion.57-65 Bank erosion = 9.5'.58-03 RSC =F4 (trans G4)58-38 Willow tree is given new Tag 1. The tree slumped in from
4' but it is presently at water surface level of pool. DBH = 23".The pool = 3' deep.
60-00 Sediment deposition on LB high terrace.60-36 Bank erosion = 7.9'.60-68 Bank erosion = 6.2'. Orondo vegetation present.62-27 RSC = F4 (trans G4)62-76 LB erosion = 5.3'.63-71 Right bank bend eroding near structure.64-53 Silt stone bedrock in channel bed.65-14 Bay tree across terrace banks.69-90 Continuous rip rap and sad bags on LB or RB to this station
from about 66-20.70-50 RSC = G4 .70-64 Pool, begin rip rap LB.71-75 End LB rip rap.72-34 Photo 103-105,(R5P22-24), looking UST at RB erosion.
RSC = F4.72-41 ' Bank undercut = 9.7'. Terrace = 11.8'72-78 RB erosion = 8.3'.73-16 l' CMP at RB.73-90 Photo RSP25, (last picture on roll not developed) looking at
RB erosion. This may be about where Photo 107 is located.75-00 Photo 111 (R6-P1), looking UST at Simmons Bridge. Notice
exposed root along low flow bank.75-80 DST end of Simmons Bridge.76-18 Culvert to Simmons Creek at LB76-23 Photo IJ4 (R6P2), looking DST beneath Simmons Bridge.
Station number pertains to UST end of Simmons Bridge.76-64 Orondo on LB77-24 Channel aggraded upstream of bridge.77-68 Photo 117 (R6P3) and 121 (R6P4), looking at RB tree that is
leaning in toward channel. Pool at old ash tree with DBH = 24.5",tree Tag 2.
79-83 Photo 124 (R6P5), looking UST along fairly stable reach.RSC = F4
80-28 Begin RB rip rap.80-51 End RB rip rap.
7
80-66 RB 15" Rep.81-00 Photo 125 (R6P6), looking usr into stable channel
RSC =F482-64 Begin LB rip rap & pool.83-55 End LB rip rap.85-04 'Photo 129 (R6P7), looking UST into fairly stable reach that
has a steeper gradient and narrower width than previous sections.There is also more cobble and occasional boulders.
86-11 Pool in narrow BDRK section. RSC = G4.86-68 RB BDRK = serpentinite.87-22 Photo 130 (R6P8).looking DST along narrow BDRK gorge =
7.7' wide.89-11 BDRK pool, Wbf = 22', bank erosion = - 2'.90-1 7 RB erosion = 3', end of BDRK reach.90-42 Boulder pool. '90-64 Small amount of BDRK and also an LB concrete crib wall.91-31 Grouted sacrete on RB.91-51 Rip rap pool.92-06 Rip rap and grouted concrete ends on RB.92-49 Begin concrete and wood retaining wall RB.92-71 End concrete and wood retaining wall RB93-12 BDRKpool93-00 Photo 135 (R6P9), looking DST at LB bedrock reach.93-12 Large, old RB willow, DBH = - 30", Tag 3. Located along
bankfull (7), about 3' higher than the mean bed level.93-28 Old weir with flash board in BDRK segment of channel.94-26 RB erosion = 3.5'. Continuous erosion to 94-88.94-52 RB erosion = 5'.94-60 RB erosion =9'95-38 LB bank erosion = 4.5". RB bank erosion = 1'.96-00 18" RCP at LB.96-33 LB tributary confluence. 1-2' diameter pipe, and 2-5'
diameter pipes99-00 RSC = F4, RB bank erosion = 4', LB bank erosion = 1.5'.99-22 RB erosion - 6.5'.99-64 15" RCP at RB, and LB erosion = 7'.100-32 Photo 151 -153 (R6P10-12), looking DST at section 9-83.
Channel widens substantially in this reach.100-78 This section of channel narrows with a tree that has been
cut after it feel in the channel. .101-51 Photo 156 (R6P13-14), looking DST at RB oak tree that has
fallen over. The exposed small roots indicate recent indsion of1.5' following a period of bed stability, while the exposed
8
moderate-sized roots show about 2' additional incision followingsome other period of stability. The previous flood plain has beenabandoned. Wbf = 25.5'. If oak is to be saved, it needs somesupport beneath the roots.
102-56 Begin RB rip rap.102-65 2' RCP.102-81 10" RCP.102-93 End RB rip rap.103-19 Photo 156 (R6P15), looking at old valley oak (?) behind
aparttnents on RB, DBH = 3.7'. The address for this site is 1730Novato Blvd. The height of the trunk/root transition is 9.' fromthe mean bed level. The terrace is 14.45' from the bed. Oldstable banks exist at about 5.' and 7.5' above the mean bed level.Tree Tag 4. RB erosion = 6.5'. The tree should be dated. Twoperiods ofindsionare apparent first 2.35' and then 2.5'. Eachseems to have been followed by a period of relative stability.Since oak trees do not grow at bankfull elevation and are found onabandoned terraces, then the floodplain that used to be located atthe 9.85' level was probably abandoned before the turn of thecentury. If present bankfull is around 4.5' to 5' high on the bank,then there has been at least 4.5' indsion during this century.
105-68 3' RCP. Abundant sand in this area.106-33 Bank erosion = 7.5'.106-61 5" PVC pipe at RB.106-90 Bank erosion = 5'.107-52 Begin RB wire basket gabbion.108-00 Photo 161 (R6P16), looking at the RB gabbion that has
bowed-out due to possible landslide creep. End wire basketgabbion, begin RB sacrete. From this station to 110-61 there isabundant fine sediment in the channel and few pools.
108-15 Photo 132-162 (R6P17-18), looking UST at RB erosionwhere the channel cuts along the nose of a hillside ridge. Channelgradient steepens along here. End RB sacrete, begin RB bedrock.Note boulders in this reach which is unusual for Novato Creek.Begin RB Bedrock
109-71 LB erosion = 3.5', RB erosion = 3.0'. Note that flood controlperiodically mows vegetation from channel bars.
112-61 First pool in this section. RB erosion = 5.0', LB erosion =1.5'.
112-99 End RB BDRK.113-92 Photo 165 (R6P19) looking UST at LB slabs. Begin concrete
slabs on LB.
9
114-69 Photo 168-169 (R621-22), looking DST at LB slabs stackedalong the bank. This station pertains to the UST end of theconcrete slabs on LB.
115-00 Photo 171 (R6P20), looking at RP bay tree along MiwokPark, tree Tag 5, DBH == 60". The root/trunk transition is at 11',but the tree may have slumped in from the 12.5' terrace. Twoperiods of relative bank stability are indicated by the exposedroots. Bank tops were previously 5.5' and 3.7' above the presentmean bed level. This reach has much more sediment storage asgravel bars. RSC= F4
116-32 Begin LB rip rap.117-17 Photo 178 (R6P23), looking UST at rip rap along the banks
near Miwok footbridge. Station is the DST end of Miwok Bridge.117-50· Approximate end LB rip rap.117-75 . Photo 189 (R6P24), looking UST at LB tributary confluence
with 2-5' Reps. One is dogged with sediment and has lost"'" 1/3of its capadty.
119-07 Photo 185 (R6P25), looking at LB erosion. LB erosion = 7',RB erosion == 1.3':
119-48 RSC= G4120-14 Old cement weir.120-25 Photo 193 (R6P26), looking at RB slide along the nose of
hillside ridge that is just upstream of old weir that used to damthe creek for fishing derbies. Other weir sites were reportedlyused for water supply for irrigation (liz Lewis).
121-41 End of RB hillside knob, begin RB terrace.121-52 Photo 194 (R6P27), Looking DST at gravel bar behind weir.
The weir has caused a noticeable increase in gravel depositionupstream while there is much more sand DST of the weir.Photo 195 (R6P28), looking upstream from weir.
122-72 LB bank erosion == 2', RB bank erosion == 1.5. Transitionfrom a Rosgen G type channel to an F type.
123-47 Pool and RB erosion == 8' beneath bay tree.123-95 Begin knob and BDRK slide on RB.124-59 Sandstone BDRK in channel bed.125-19 Photo 199 (R6P29), looking DST at RB bay tree that has
fallen at eroding bend in channel.126-88 Photo 202 (R6P30), looking DST from 127-25 at LB bank
erosion = 5'. RB erosion == 0.5'. Channel reach is F type.128-23 Old channel sediments exposed in RB terrace.128-91 Channel changes again from an F type to a G type.130-70 Photo 206 (R6P31), looking UST toward Novato Blvd bridge.
10
Photo 204 (R6P32), looking DST from below Novato Blvdbridge. Marin Flood Control District does not manage streamabove the bridge.
130-57 Begin RB concrete wall.130-82 End RB concrete wall.130-92 Begin concrete rip rap in bed.132-17 End concrete rip rap in bed.131-00 RB tributary confluence with 4' RCP.131-40 DST end Novato Bridge, begin I.B and RB grouted rip rap.132-77 Photo 207 (R6P33), looking DST at UST end Novato
Blvd Bridge.132-86 End I.B rip rap.133-06 End RB rip rap.134-00 Photo 208 (R6P34), looking UST from Novato Blvd Bridge
where gravel bars are less sandy, and the banks are not soeroded.
134-81 RSC= F4 (G4 transition, bank erosion = 6'.136-30 Photo 209 (R6P35), looking UST at recent LB erosion and a
fallen willow at 136-68.136-68 Photo 210 (R6 P36), looking at LB terrace banks that supply
medium-sized gravels and sand from erosion at bend.138-55 Photo 211 (R6P37), looking DST from 138-90 at concrete
slabs that may have been a weir. The channel is also constrictedby a fallen willow on RB and willow branches from LB Lots ofgravel bars noted upstream of the constricted site.
139-15 Photo 212-213 (R7PI-2), looking UST at Bay tree acrosschannel that has fungal rot in its trunk. LB erosion = 3.5', RBerosion = 1.5'.
139-22 LB erosion = 5', RB erosion = 1.5'.140-80 LB erosion = 4.5'.140-94 Lots of recent deposition of sand and fme gravel.141-90 Channel is very aggraded with lots of sediment storage
bars of gravel and fine gravels and sand in the bed resulting inan apparent loss of capacity. This may represent a slug ofsediment moving downstream. Bank erosion = 8' in some areas.
143-22 The aggraded reach has ended, but there was lots of bankerosion in the reaches before this point.
144-45 DST end of private driveway bridge (with dog).146-29 Bank erosion = 4.5'.146-69 Photo 214-215 (R7P3-4), looking DST at large gravel bar on
the RB is at least 2' high. LB erosion = 4.5'., RB erosion = 2.0'.149-38 DST edge of private driveway bridge. Gravel bars are
about 3' high. Begin RB rip rap. RSC= G4, bank erosion = 4.5'.
11
, 12
149-48 End RB rip rap.150-00 Bank erosion =5'.150-26 Photo 216(R7P5), looking DST to bridge. Bank erosion = 5.5'.
Gravel bar is 3' high..150-75 Begin LB rip rap. Channel still appears aggraded. This
could be due to a former debris jam that could have fonnedupstream of the bridge.
151-24 Photo 217 (R7P6), looking DST at 7' high water mark in RBash tree that is growing at 2.25' on low bank. OBH = 0.5'. Notehigh bar on RB is 2.7'. Bank erosion since the establishment of theash tree is 3.5'. This tree should be dated.
151-84' Photo 218 (R7P7), looking at RB tributary confluence whichis graded to Novato Creek thalweg. Fence structure couldpotentially increase channel blockage.
153-10 Begin LB rip rap.153-39 End LB rip rap.153-41 Begin LB rip rap.153-77 End LB rip rap.153-85 LB bank erosion = 4.5'.154-74 Photo 219 (R7P8), looking UST at Sutro Bridge. Begin RB rip
rap.155-34 End RB rip rap.156-17 OST end ofSutro Bridge.156-72 Photo 220 (R7P9), looking OST at UST end of Sutro Bridge.'
The bridge has a cement bottom that sets grade of channel Lessthan l' of ,sediment deposition on LB side of bridge.
157-59 Photo 221 (R7-PI0), looking UST at sand bag clam for fishingderby at horse stables area.
159-00 RB erosion = 3'159-38 Photo 223 (R7Pl1), looking at RB erosion beneath undercutoak tree. RB erosion = 7'. This would be a good tree to date to
detennine rate of bank loss.159-75 Bay tree leaning across channel159-97 Water diversion pump.161-07 RB oak tree top in channel.161-34 Photo 224 (R7PI2), looking upstream at F type channel. The
terrace height along this reach appears low relative to the bedheight.
162-00 Photo 225 (R7PI3), looking at LB bay trees of l' DBH. Theyare growing about 2.6' above the mean bed level (bankfull?).Bank erosion exposing roots = 1-2'. These would be good trees todate. RSC= F4
162-92 Bedrock across bed and bay tree partially across channel.
163-53 Bank erosion = 3.5'.165-00 Photo 226 (R8P3), looking UST where channel narrows and
RB hillslope, rather than terrace is adjacent to channel.165-90 RSC= F4169-93 Photo 227 (R8P6), looking DST End bedrock influenced
reach. Channel widens slightly upstream.170-59 Confluence RB tributary/gully from road, graded to
bankfull flow. Male Wilson's warbler observed singing inriparian vegetation.
172-77 Photo 228 (R8P8), looking UST where widening of channeland magnitude of gravel bars is more significant.
173-20 Bank erosion = 3'.174-36 Photo 230-233 (R8P9-11), looking DST at large RB point bar
and LB erosion.175-25 Confluence LB tributary that is not graded to Novato
Creek. It is gullied just at confluence and does not carry much'sediment load.
176-21 Photo 234 (R8P12), looking UST at bay tree in channel176-55 Bay tree in Channel. Lots of bank erosion upstream on LB.177-00 Photo 235 (R8P13), looking UST at LB erosion =:= 3.5'.178-48 RB erosion = 2.5'.180-40 Bank erosion .... 2.5'.181-84 Photo 236 (R8P14), looking UST at fallen bay tree from RH.
RB erosion = 6'.182-70 Photo 237 (R8P15). Two 6" trout observed to be spawning
in upstream of the pool. Also a singing male Wilson's warbler wasobserved.
183-14 Fry in riffle.185-85 Photo 238-239 (R8P16-17), looking DST at RB bay tree in
channel and area where pools and riffles have developed inassociation with large point bars. Some bars nearly got to top ofterrace banks behind blown out debris jams. RB erosion = 5.7'.
186-51 Photo 240 (R8P18), looking UST at DST end of old bridge.More Fry observed upstream of bridge at 186-79.Photo 241-242 (R8P19-20), looking DST from bridge(?) atriffles and gravel bars.
188-25 LB erosion = 9'.188-76 Frog in creek, possible red legged? RSC= G4189-94 Photo 243-245 (R8P21-23), looking DST at floodplain-level
bar or old bed along the LB. Also note Wilson's warbler singing.RSC= B4
192-14 Photo 246 (R8P24), looking DST at blown out dam that has a4' step in grade at its DST end.
13
192-95 RB willow has fallen into channel.193-48 Singing Bullocks Oriole, 5/5/97.193-63 LB erosion = 2.5'.194-29 A 4" trout obsenred in pool.194-44 Bank erosion = 6'.195-48 Photo 247 (R8P25), looking UST at wide reach of channel.
This reach has mid channel and lateral bars. RSC= B4195-89 RB erosion =4'.196-69 Photo 248-250 (R8P26-28), looking upstream at B type
channel where willow has fallen into channel.197-37 Tree down in channel.198-00 Photo 251 (R8P29), looking DST in cutoff oxbow channel on
LB.Photo 252 (R8P30), looking UST in old oxbow cutoff. Theterrace is about 5' above the oxbow bed.Wbf Ill: 22.5 Dmn Ill: 3.2 CAbf == 72 Dmx == 4WDR= 7.03There is a 17" DBH bay tree 1.6' above the oxbow bed, which hasprobably filled somewhat since it became cut off.Photo 253 (R8P31), looking DST in oxbow at a 1.4' DBH willowpractically in the bed of the channel at the DST end of itsconfluence with the main channel.
199-71 UST end of cutoff meander that is 5.5' above the mean bedlevel of main Novato Cr. There are 1.5' of fines over gravels in the oxbow bed at its confluence, indicating the possible amount offilling.Photo 254 (R8P32), looking upstream above oxbow cutoffconfluence.
200-46 Bend with 2 obvious terrace levels. The highest is on theRB.
200-90 Terrace heights which are different on both sides of thechannel (higher on the LB). RB erosion == 7.5'. LB erosion = 5.2' for- 37'.
202-90 Photo 255-256 (R8P33-34), looking DST at RB where personis standing on a prominent inner bank. RB erosion = 8'.
203-53 Photo 257 (R8P35), looking UST at LB erosion = 7'.204-227 Photo 258 (R8P36), looking DST at fallen RB bay tree.204-49 LB willow tree with DBH of 1.8' on terrace at 5.8' above
mean.bed level.204-92 Bay tree in channel.205-08 Bull frog identified.206-27 Blown-out debris jam.
14
206-30 Photo 259 (R9Pl), looking at LB willow in old channel. Twotrees in an old cut off channel. Willow tree = Tag 6. DBH =36" located 5.5' below terrace and 2' above old channel bed. Theold bed is a maximum of 7.4' above the present bed level.elderberry tree DBH = 0.6' at bed.Photo 260 (R9P6), looking DST at meander cut off.
208-04 RB erosion = 3'.209-15 Photo 261 (R9P2), LB (7) willow (given Tag 7) has DBH =
36" at 6.5' below terrace and 6,6' above present bed level.209-50 Major LB erosion = 14.5'. Channel is very wide.209-90(7) Photo 262 (R9P3), looking UST at tree fall and RB erosion.
Photo 263 (R9P4), looking DST at woody debris in middle ofchannel.
210-67 RB erosion =12'.210-82 RB gravel bar = 2.2'.211-87 RB erosion = 4.5', LB erosion = 1'.212-15 Photo 265-266 (R11P8-9), looking DST at cross section
area. See Cross Section Survey 121-15, Figure 17A in report.212-53 RB debris flow chute from hillslope, not presently active.213-63 LB erosion = 10.7.214-09 Photo 267-268 (RI0P36-37), looking UST at LB where there
has been substantial bank erosion. Bay trees on the terrace aregone although remnants of their roots are still present. Terraceheight = 13'.
214-11 Photo 269 (RIIPI), looking at RB pond where a bull frogtadpole was observed. This is the first off-channel habitat (forlow flow) that has been observed along Novato Cr.Photo 270-271 (RIIP2-3), looking DST toward LB erosion seen inPhoto 267-268. Note that the pond is just to the right of thedebris shown in the right center of the photo.
214-85 Photo 267 (RI1P10) looking at LB cliff swallow nest.214-90 Photo 268 (RIIP7), looking DST at cross section. See
Cross Section Survey 214-90, Figure 17B in report.215-10 Photo 274 (RI1P5), looking UST at another off-channel pond
on RB. Both ponds occur where there is woody debris anchored inlarge gravel bars, that only occur where the width of the channelhas been substantially increased from bank and terrace erosion.
215-1 7 Salmonids in pool.215-95 Change to bedrock in banks, channel narrows and much less
erosion.216-46 Photo 275 (RIIP6), looking DST at cross section. See Cross
Section Survey 216-46, Figure 17B in report.
15
16
217-07 LB bar about 7.1' below terrace, and bed is about 6.8'below top of bar. The bar may be in an abandoned bend.
217-66(218-667) Willow on abandoned channel bed. DBH = 18",Tag 8. Another willow near this location has a DBH = 17.2"
217-90(218-907) LB bay tree, Tag 9, which has a DBH = 17" and isgrowing on the bed of an abandoned meander.Photo R276 (11P14), looking at RB Bay tree Tag 10, growing atpossible edge of bank, has a DBH = 13.6". The old bed is about 4.1'below the edge of the terrace.
218-44 Photo 277 R11P11) Looking DST at old Plymouth inchannel.
218-82 Photo 278-279 (R11P12-13), looking UST where channelwidens significantly toward the confluence with Bowman Canyon.
219-37 . Photo 280 (R11P15), looking at LB willow, tree Tag 11,that has a DBH =0.6'. It is growing on a bar that is 4' above thethalweg and 7.5' below the terrace banks.
220-02 There is a metal tank in the middle of the channel thatforms a pool filled with Salmonids. This each has lots ofsediment stored in high gravel bars.
220-51 Centerline of confluence with Bowman Canyon Cr.221-06 RB erosion =3.5'. RB bar = 4.4' above thalweg.221-68 RB erosion =3.5'. Note that above Bowman the channel
has lots of bars at many different levels, suggesting that flow isinsufficient to move sediment but most appears to be trappeddue to woody debris and vegetation encroachment up to Station223-00.
222-86 (7) LB erosion = 3'.0223-00 Photo 281 (RI1P17), looking UST where channel narrows
and becomes' relatively stable. Sediment storage appears limitedand there is little vegetation encroachment.
223-25 Photo 282 (RI1PI6), looking at LB eroding gully withexposed roots of bay tree. The gully has been caused by excessrunoff from grazed field.
223-94 RB erosion = 4', LB undercut = 2'.224-13 Begin bedrock in banks.226-61 RSe= B,F,G47 Terrace height = 12.4', bank erosion = 2'.228-14 Photo 283 (RIIPI8), looking at UST car wreck (Rambler 7)228-65 Photo 284-285 (R11P19-20), looking UST at bank erosion =
37', fallen trees and midchannel bars that are 2' high. There isample localized sediment supply from the banks.
229-05 Photo 286 (RIIP21), looking UST at LB erosion = 5'231-00 Photo 287 (RI1P22), looking UST at RB inner gorge and bank
erosion.
231-68 Photo 288 (RIIP23), looking at willow, tree Tag 12, onmidchannel bar. DBH == 8".
233-14 Photo 289 (RIIP24), looking DST at large point bar withstable vegetation. Near this station there is an old channel bedabout SA' above the thalweg on RB. Add 0.5' to roots that areexposed indicating that the bed was 6' above the thalweg. Theterrace on RB is 8.6' above the bar/bed feature.
233-31 RB debris flow track at ephemeral tributary opposite thepoint bar, which is 5.s' below the terrace. The bar may be an old
floodplain.233-91 LB erosion ==52'. The channel changes to major bank
-- erosion with braided channels occurring both above and belowthe previous bankfull elevation.Photo 290 (RIIP25), looking toward the LB from the top ofthe terrace where the old fence is missing.
234-14 Trout pool.235-12 Bull frog in pond upstream of debris jam.236-15 Upstream extent of extreme 52' wide LB erosion.237-00 Photo 291 (R11P26), looking DST at UST end of debris jam.
The channel is choked with vegetation and sediment from aboutstation 235-15 to this station. The LB is also eroding.
238-08 Five newts observed.238-46 Photo 292 (RIIP27), looking UST at cross section. See
Cross Section Survey 238-46, Figure 17C in report.240-00 Channel appears aggraded in long straight reach. There are
no pools and terrace is only 9.8' above the bed.241-37 BDRKin RB.241-95 Photo 293 (R11P28), looking UST at RB debris flow chute
along a tributaIy with exposed roots.244-70 Photo 294-295 (R11P29-30), looking DST at debris jam from
fallen bay tree.247-13 RB tributaIy with sediment supply disconnected from main
stem Novato Cr.247-34 Photo 296 (R11P31), looking at LB erosion where bay tree
has collapsed into channel. Terrace height is 13.9' above thethalweg.
249-06 LB erosion == 6'.25).-47 Photo 297 (R11P32), looking at LB erosion == 5. RB erosion ==4', and recent bed incision == 2.2'.252-89 The channel bed is armored with coarse gravel. The supply
is from local terrace banks.255-38 Lazuli bunting sighted, 5/21/97.255-14 Begin RB rip rap.
17
255 ..78 End RB rip rap.256..03 Confluence of LB tributary (Leveroni). The main Novato Cr
channel has a fallen willow and overhanging vegetation blockingthe main stem at the upstream end of the confluence to station256-60.
256-93 Photo 298 (R12P22), looking DST at LB oak tree on ivy"covered bank.
257-1 Photo 299 (R12P23), looking UST at willow that has falleninto channel. This section is narrow and has lots of small willowsin the channel. Fine and gravel-sized sediment is present withlots of large rip rap pieces and broken culvert parts scattered inthe channel bed.
259-78 Photo 300 (R12P24) looking at RB RCP outflow for reservoir.Above this station toward the spillway structure, there isevidence of past significant bank eroSion that has stabilized.There are lots of willows choking the channel bed through thissection.
261-80 Begin rip rap in channel bed.261-95 Begin concrete/rip rap channel bed.262-65 Photo 301 (R12P25), looking UST at beginning of cement
spillway.
18
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LEGEND OF OWNERSHIP
MARIN COUNTY FLOOD CONTROL DISTRICT
CITY OF NOVATO
NOVATO UNIFIED SCHOOL DISTRICT
MAINTAINED BY MARIN COUNTY FLOOD CONTROL
COUNTY OF MARINCOMMUNITY DEVELOPMENT AGENCY MAPPING/GRAPHICSSCALE: 1" = 300 APRIL 6, 1998 FILES: A AVICHI.DWG. A_AVICHl.PLTTHIS MAP IS REPRESENTATIONAL ONLY. DATA ARE NOT SURVEY ACCURATE.
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